Solve by Substitution x^2+4y^2=16 , 6x^2-y^2=12

$x^{2} + 4 y^{2} = 16$ , $6 x^{2} - y^{2} = 12$

Step 1

Solve for $x$ in $x^{2} + 4 y^{2} = 16$ .

Subtract $4 y^{2}$ from both sides of the equation.

$x^{2} = 16 - 4 y^{2}$

$6 x^{2} - y^{2} = 12$

Take the specified root of both sides of the equation to eliminate the exponent on the left side.

$x = \pm \sqrt{16 - 4 y^{2}}$

$6 x^{2} - y^{2} = 12$

Simplify $\pm \sqrt{16 - 4 y^{2}}$ .

Factor $4$ out of $16 - 4 y^{2}$ .

Factor $4$ out of $16$ .

$x = \pm \sqrt{4 (4) - 4 y^{2}}$

$6 x^{2} - y^{2} = 12$

Factor $4$ out of $- 4 y^{2}$ .

$x = \pm \sqrt{4 (4) + 4 (- y^{2})}$

$6 x^{2} - y^{2} = 12$

Factor $4$ out of $4 (4) + 4 (- y^{2})$ .

$x = \pm \sqrt{4 (4 - y^{2})}$

$6 x^{2} - y^{2} = 12$

$x = \pm \sqrt{4 (4 - y^{2})}$

$6 x^{2} - y^{2} = 12$

Rewrite $4$ as $2^{2}$ .

$x = \pm \sqrt{4 (2^{2} - y^{2})}$

$6 x^{2} - y^{2} = 12$

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = 2$ and $b = y$ .

$x = \pm \sqrt{4 (2 + y) (2 - y)}$

$6 x^{2} - y^{2} = 12$

Rewrite $4 (2 + y) (2 - y)$ as $2^{2} ((2 + y) (2 - y))$ .

Rewrite $4$ as $2^{2}$ .

$x = \pm \sqrt{2^{2} (2 + y) (2 - y)}$

$6 x^{2} - y^{2} = 12$

Add parentheses.

$x = \pm \sqrt{2^{2} ((2 + y) (2 - y))}$

$6 x^{2} - y^{2} = 12$

$x = \pm \sqrt{2^{2} ((2 + y) (2 - y))}$

$6 x^{2} - y^{2} = 12$

Pull terms out from under the radical.

$x = \pm 2 \sqrt{(2 + y) (2 - y)}$

$6 x^{2} - y^{2} = 12$

$x = \pm 2 \sqrt{(2 + y) (2 - y)}$

$6 x^{2} - y^{2} = 12$

The complete solution is the result of both the positive and negative portions of the solution.

First, use the positive value of the $\pm$ to find the first solution.

$x = 2 \sqrt{(2 + y) (2 - y)}$

$6 x^{2} - y^{2} = 12$

Next, use the negative value of the $\pm$ to find the second solution.

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$6 x^{2} - y^{2} = 12$

The complete solution is the result of both the positive and negative portions of the solution.

$x = 2 \sqrt{(2 + y) (2 - y)}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$6 x^{2} - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$6 x^{2} - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$6 x^{2} - y^{2} = 12$

Step 2

Solve the system $x = 2 \sqrt{(2 + y) (2 - y)}, 6 x^{2} - y^{2} = 12$ .

Replace all occurrences of $x$ with $2 \sqrt{(2 + y) (2 - y)}$ in each equation.

Replace all occurrences of $x$ in $6 x^{2} - y^{2} = 12$ with $2 \sqrt{(2 + y) (2 - y)}$ .

$6 {(2 \sqrt{(2 + y) (2 - y)})}^{2} - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Simplify the left side.

Simplify $6 {(2 \sqrt{(2 + y) (2 - y)})}^{2} - y^{2}$ .

Simplify each term.

Apply the product rule to $2 \sqrt{(2 + y) (2 - y)}$ .

$6 (2^{2} {\sqrt{(2 + y) (2 - y)}}^{2}) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Raise $2$ to the power of $2$ .

$6 (4 {\sqrt{(2 + y) (2 - y)}}^{2}) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Rewrite ${\sqrt{(2 + y) (2 - y)}}^{2}$ as $(2 + y) (2 - y)$ .

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{(2 + y) (2 - y)}$ as ${((2 + y) (2 - y))}^{\frac{1}{2}}$ .

$6 (4 {({((2 + y) (2 - y))}^{\frac{1}{2}})}^{2}) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$6 (4 {((2 + y) (2 - y))}^{\frac{1}{2} \cdot 2}) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Combine $\frac{1}{2}$ and $2$ .

$6 (4 {((2 + y) (2 - y))}^{\frac{2}{2}}) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Cancel the common factor of $2$ .

Cancel the common factor.

$6 (4 {((2 + y) (2 - y))}^{\frac{2}{2}}) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Rewrite the expression.

$6 (4 ((2 + y) (2 - y))) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$6 (4 ((2 + y) (2 - y))) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Simplify.

$6 (4 ((2 + y) (2 - y))) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$6 (4 ((2 + y) (2 - y))) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Expand $(2 + y) (2 - y)$ using the FOIL Method.

Apply the distributive property.

$6 (4 (2 (2 - y) + y (2 - y))) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Apply the distributive property.

$6 (4 (2 \cdot 2 + 2 (- y) + y (2 - y))) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Apply the distributive property.

$6 (4 (2 \cdot 2 + 2 (- y) + y \cdot 2 + y (- y))) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$6 (4 (2 \cdot 2 + 2 (- y) + y \cdot 2 + y (- y))) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Simplify and combine like terms.

Simplify each term.

Multiply $2$ by $2$ .

$6 (4 (4 + 2 (- y) + y \cdot 2 + y (- y))) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Multiply $- 1$ by $2$ .

$6 (4 (4 - 2 y + y \cdot 2 + y (- y))) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Move $2$ to the left of $y$ .

$6 (4 (4 - 2 y + 2 \cdot y + y (- y))) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Rewrite using the commutative property of multiplication.

$6 (4 (4 - 2 y + 2 y - y \cdot y)) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Multiply $y$ by $y$ by adding the exponents.

Move $y$ .

$6 (4 (4 - 2 y + 2 y - (y \cdot y))) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Multiply $y$ by $y$ .

$6 (4 (4 - 2 y + 2 y - y^{2})) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$6 (4 (4 - 2 y + 2 y - y^{2})) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$6 (4 (4 - 2 y + 2 y - y^{2})) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Add $- 2 y$ and $2 y$ .

$6 (4 (4 + 0 - y^{2})) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Add $4$ and $0$ .

$6 (4 (4 - y^{2})) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$6 (4 (4 - y^{2})) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Apply the distributive property.

$6 (4 \cdot 4 + 4 (- y^{2})) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Multiply $4$ by $4$ .

$6 (16 + 4 (- y^{2})) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Multiply $- 1$ by $4$ .

$6 (16 - 4 y^{2}) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Apply the distributive property.

$6 \cdot 16 + 6 (- 4 y^{2}) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Multiply $6$ by $16$ .

$96 + 6 (- 4 y^{2}) - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Multiply $- 4$ by $6$ .

$96 - 24 y^{2} - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$96 - 24 y^{2} - y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Subtract $y^{2}$ from $- 24 y^{2}$ .

$96 - 25 y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$96 - 25 y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$96 - 25 y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$96 - 25 y^{2} = 12$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Solve for $y$ in $96 - 25 y^{2} = 12$ .

Move all terms not containing $y$ to the right side of the equation.

Subtract $96$ from both sides of the equation.

$- 25 y^{2} = 12 - 96$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Subtract $96$ from $12$ .

$- 25 y^{2} = - 84$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$- 25 y^{2} = - 84$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Divide each term in $- 25 y^{2} = - 84$ by $- 25$ and simplify.

Divide each term in $- 25 y^{2} = - 84$ by $- 25$ .

$\frac{- 25 y^{2}}{- 25} = \frac{- 84}{- 25}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Simplify the left side.

Cancel the common factor of $- 25$ .

Cancel the common factor.

$\frac{- 25 y^{2}}{- 25} = \frac{- 84}{- 25}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Divide $y^{2}$ by $1$ .

$y^{2} = \frac{- 84}{- 25}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$y^{2} = \frac{- 84}{- 25}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$y^{2} = \frac{- 84}{- 25}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Simplify the right side.

Dividing two negative values results in a positive value.

$y^{2} = \frac{84}{25}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$y^{2} = \frac{84}{25}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$y^{2} = \frac{84}{25}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Take the specified root of both sides of the equation to eliminate the exponent on the left side.

$y = \pm \sqrt{\frac{84}{25}}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Simplify $\pm \sqrt{\frac{84}{25}}$ .

Rewrite $\sqrt{\frac{84}{25}}$ as $\frac{\sqrt{84}}{\sqrt{25}}$ .

$y = \pm \frac{\sqrt{84}}{\sqrt{25}}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Simplify the numerator.

Rewrite $84$ as $2^{2} \cdot 21$ .

Factor $4$ out of $84$ .

$y = \pm \frac{\sqrt{4 (21)}}{\sqrt{25}}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Rewrite $4$ as $2^{2}$ .

$y = \pm \frac{\sqrt{2^{2} \cdot 21}}{\sqrt{25}}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$y = \pm \frac{\sqrt{2^{2} \cdot 21}}{\sqrt{25}}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Pull terms out from under the radical.

$y = \pm \frac{2 \sqrt{21}}{\sqrt{25}}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$y = \pm \frac{2 \sqrt{21}}{\sqrt{25}}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Simplify the denominator.

Rewrite $25$ as $5^{2}$ .

$y = \pm \frac{2 \sqrt{21}}{\sqrt{5^{2}}}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Pull terms out from under the radical, assuming positive real numbers.

$y = \pm \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$y = \pm \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$y = \pm \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

The complete solution is the result of both the positive and negative portions of the solution.

First, use the positive value of the $\pm$ to find the first solution.

$y = \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Next, use the negative value of the $\pm$ to find the second solution.

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

The complete solution is the result of both the positive and negative portions of the solution.

$y = \frac{2 \sqrt{21}}{5}, - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$y = \frac{2 \sqrt{21}}{5}, - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

$y = \frac{2 \sqrt{21}}{5}, - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{(2 + y) (2 - y)}$

Replace all occurrences of $y$ with $\frac{2 \sqrt{21}}{5}$ in each equation.

Replace all occurrences of $y$ in $x = 2 \sqrt{(2 + y) (2 - y)}$ with $\frac{2 \sqrt{21}}{5}$ .

$x = 2 \sqrt{(2 + \frac{2 \sqrt{21}}{5}) (2 - (\frac{2 \sqrt{21}}{5}))}$

$y = \frac{2 \sqrt{21}}{5}$

Simplify $x = 2 \sqrt{(2 + \frac{2 \sqrt{21}}{5}) (2 - (\frac{2 \sqrt{21}}{5}))}$ .

Simplify the left side.

Remove parentheses.

$x = 2 \sqrt{(2 + \frac{2 \sqrt{21}}{5}) (2 - (\frac{2 \sqrt{21}}{5}))}$

$y = \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{(2 + \frac{2 \sqrt{21}}{5}) (2 - (\frac{2 \sqrt{21}}{5}))}$

$y = \frac{2 \sqrt{21}}{5}$

Simplify the right side.

Simplify $2 \sqrt{(2 + \frac{2 \sqrt{21}}{5}) (2 - (\frac{2 \sqrt{21}}{5}))}$ .

To write $2$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$x = 2 \sqrt{(2 \cdot \frac{5}{5} + \frac{2 \sqrt{21}}{5}) (2 - \frac{2 \sqrt{21}}{5})}$

$y = \frac{2 \sqrt{21}}{5}$

Combine $2$ and $\frac{5}{5}$ .

$x = 2 \sqrt{(\frac{2 \cdot 5}{5} + \frac{2 \sqrt{21}}{5}) (2 - \frac{2 \sqrt{21}}{5})}$

$y = \frac{2 \sqrt{21}}{5}$

Simplify the expression.

Combine the numerators over the common denominator.

$x = 2 \sqrt{\frac{2 \cdot 5 + 2 \sqrt{21}}{5} \cdot (2 - \frac{2 \sqrt{21}}{5})}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $2$ by $5$ .

$x = 2 \sqrt{\frac{10 + 2 \sqrt{21}}{5} \cdot (2 - \frac{2 \sqrt{21}}{5})}$

$y = \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{10 + 2 \sqrt{21}}{5} \cdot (2 - \frac{2 \sqrt{21}}{5})}$

$y = \frac{2 \sqrt{21}}{5}$

To write $2$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$x = 2 \sqrt{\frac{10 + 2 \sqrt{21}}{5} \cdot (2 \cdot \frac{5}{5} - \frac{2 \sqrt{21}}{5})}$

$y = \frac{2 \sqrt{21}}{5}$

Combine fractions.

Combine $2$ and $\frac{5}{5}$ .

$x = 2 \sqrt{\frac{10 + 2 \sqrt{21}}{5} \cdot (\frac{2 \cdot 5}{5} - \frac{2 \sqrt{21}}{5})}$

$y = \frac{2 \sqrt{21}}{5}$

Simplify the expression.

Combine the numerators over the common denominator.

$x = 2 \sqrt{\frac{10 + 2 \sqrt{21}}{5} \cdot \frac{2 \cdot 5 - 2 \sqrt{21}}{5}}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $2$ by $5$ .

$x = 2 \sqrt{\frac{10 + 2 \sqrt{21}}{5} \cdot \frac{10 - 2 \sqrt{21}}{5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{10 + 2 \sqrt{21}}{5} \cdot \frac{10 - 2 \sqrt{21}}{5}}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $\frac{10 + 2 \sqrt{21}}{5}$ by $\frac{10 - 2 \sqrt{21}}{5}$ .

$x = 2 \sqrt{\frac{(10 + 2 \sqrt{21}) (10 - 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{(10 + 2 \sqrt{21}) (10 - 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Simplify the numerator.

Expand $(10 + 2 \sqrt{21}) (10 - 2 \sqrt{21})$ using the FOIL Method.

Apply the distributive property.

$x = 2 \sqrt{\frac{10 (10 - 2 \sqrt{21}) + 2 \sqrt{21} (10 - 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Apply the distributive property.

$x = 2 \sqrt{\frac{10 \cdot 10 + 10 (- 2 \sqrt{21}) + 2 \sqrt{21} (10 - 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Apply the distributive property.

$x = 2 \sqrt{\frac{10 \cdot 10 + 10 (- 2 \sqrt{21}) + 2 \sqrt{21} \cdot 10 + 2 \sqrt{21} (- 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{10 \cdot 10 + 10 (- 2 \sqrt{21}) + 2 \sqrt{21} \cdot 10 + 2 \sqrt{21} (- 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Simplify and combine like terms.

Simplify each term.

Multiply $10$ by $10$ .

$x = 2 \sqrt{\frac{100 + 10 (- 2 \sqrt{21}) + 2 \sqrt{21} \cdot 10 + 2 \sqrt{21} (- 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $- 2$ by $10$ .

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 2 \sqrt{21} \cdot 10 + 2 \sqrt{21} (- 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $10$ by $2$ .

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} + 2 \sqrt{21} (- 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $2 \sqrt{21} (- 2 \sqrt{21})$ .

Multiply $- 2$ by $2$ .

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \sqrt{21} \sqrt{21}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Raise $\sqrt{21}$ to the power of $1$ .

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 (\sqrt{21} \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Raise $\sqrt{21}$ to the power of $1$ .

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 (\sqrt{21} \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 {\sqrt{21}}^{1 + 1}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Add $1$ and $1$ .

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 {\sqrt{21}}^{2}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 {\sqrt{21}}^{2}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Rewrite ${\sqrt{21}}^{2}$ as $21$ .

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{21}$ as $21^{\frac{1}{2}}$ .

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 {(21^{\frac{1}{2}})}^{2}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \cdot 21^{\frac{1}{2} \cdot 2}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Combine $\frac{1}{2}$ and $2$ .

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \cdot 21^{\frac{2}{2}}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Cancel the common factor of $2$ .

Cancel the common factor.

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \cdot 21^{\frac{2}{2}}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Rewrite the expression.

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Evaluate the exponent.

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $- 4$ by $21$ .

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 84}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 84}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Subtract $84$ from $100$ .

$x = 2 \sqrt{\frac{16 - 20 \sqrt{21} + 20 \sqrt{21}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Add $- 20 \sqrt{21}$ and $20 \sqrt{21}$ .

$x = 2 \sqrt{\frac{16 + 0}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Add $16$ and $0$ .

$x = 2 \sqrt{\frac{16}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{16}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{16}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $5$ by $5$ .

$x = 2 \sqrt{\frac{16}{25}}$

$y = \frac{2 \sqrt{21}}{5}$

Rewrite $\sqrt{\frac{16}{25}}$ as $\frac{\sqrt{16}}{\sqrt{25}}$ .

$x = 2 (\frac{\sqrt{16}}{\sqrt{25}})$

$y = \frac{2 \sqrt{21}}{5}$

Simplify the numerator.

Rewrite $16$ as $4^{2}$ .

$x = 2 (\frac{\sqrt{4^{2}}}{\sqrt{25}})$

$y = \frac{2 \sqrt{21}}{5}$

Pull terms out from under the radical, assuming positive real numbers.

$x = 2 (\frac{4}{\sqrt{25}})$

$y = \frac{2 \sqrt{21}}{5}$

$x = 2 (\frac{4}{\sqrt{25}})$

$y = \frac{2 \sqrt{21}}{5}$

Simplify the denominator.

Rewrite $25$ as $5^{2}$ .

$x = 2 (\frac{4}{\sqrt{5^{2}}})$

$y = \frac{2 \sqrt{21}}{5}$

Pull terms out from under the radical, assuming positive real numbers.

$x = 2 (\frac{4}{5})$

$y = \frac{2 \sqrt{21}}{5}$

$x = 2 (\frac{4}{5})$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $2 (\frac{4}{5})$ .

Combine $2$ and $\frac{4}{5}$ .

$x = \frac{2 \cdot 4}{5}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $2$ by $4$ .

$x = \frac{8}{5}$

$y = \frac{2 \sqrt{21}}{5}$

$x = \frac{8}{5}$

$y = \frac{2 \sqrt{21}}{5}$

$x = \frac{8}{5}$

$y = \frac{2 \sqrt{21}}{5}$

$x = \frac{8}{5}$

$y = \frac{2 \sqrt{21}}{5}$

$x = \frac{8}{5}$

$y = \frac{2 \sqrt{21}}{5}$

$x = \frac{8}{5}$

$y = \frac{2 \sqrt{21}}{5}$

Replace all occurrences of $y$ with $- \frac{2 \sqrt{21}}{5}$ in each equation.

Replace all occurrences of $y$ in $x = 2 \sqrt{(2 + y) (2 - y)}$ with $- \frac{2 \sqrt{21}}{5}$ .

$x = 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 - (- \frac{2 \sqrt{21}}{5}))}$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify $x = 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 - (- \frac{2 \sqrt{21}}{5}))}$ .

Simplify the left side.

Remove parentheses.

$x = 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 - (- \frac{2 \sqrt{21}}{5}))}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 - (- \frac{2 \sqrt{21}}{5}))}$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify the right side.

Simplify $2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 - (- \frac{2 \sqrt{21}}{5}))}$ .

Multiply $- - \frac{2 \sqrt{21}}{5}$ .

Multiply $- 1$ by $- 1$ .

$x = 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 + 1 (\frac{2 \sqrt{21}}{5}))}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $\frac{2 \sqrt{21}}{5}$ by $1$ .

$x = 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

To write $2$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$x = 2 \sqrt{(2 \cdot \frac{5}{5} - \frac{2 \sqrt{21}}{5}) (2 + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

Combine $2$ and $\frac{5}{5}$ .

$x = 2 \sqrt{(\frac{2 \cdot 5}{5} - \frac{2 \sqrt{21}}{5}) (2 + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify the expression.

Combine the numerators over the common denominator.

$x = 2 \sqrt{\frac{2 \cdot 5 - 2 \sqrt{21}}{5} \cdot (2 + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $2$ by $5$ .

$x = 2 \sqrt{\frac{10 - 2 \sqrt{21}}{5} \cdot (2 + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{10 - 2 \sqrt{21}}{5} \cdot (2 + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

To write $2$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$x = 2 \sqrt{\frac{10 - 2 \sqrt{21}}{5} \cdot (2 \cdot \frac{5}{5} + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

Combine fractions.

Combine $2$ and $\frac{5}{5}$ .

$x = 2 \sqrt{\frac{10 - 2 \sqrt{21}}{5} \cdot (\frac{2 \cdot 5}{5} + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify the expression.

Combine the numerators over the common denominator.

$x = 2 \sqrt{\frac{10 - 2 \sqrt{21}}{5} \cdot \frac{2 \cdot 5 + 2 \sqrt{21}}{5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $2$ by $5$ .

$x = 2 \sqrt{\frac{10 - 2 \sqrt{21}}{5} \cdot \frac{10 + 2 \sqrt{21}}{5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{10 - 2 \sqrt{21}}{5} \cdot \frac{10 + 2 \sqrt{21}}{5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $\frac{10 - 2 \sqrt{21}}{5}$ by $\frac{10 + 2 \sqrt{21}}{5}$ .

$x = 2 \sqrt{\frac{(10 - 2 \sqrt{21}) (10 + 2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{(10 - 2 \sqrt{21}) (10 + 2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify the numerator.

Expand $(10 - 2 \sqrt{21}) (10 + 2 \sqrt{21})$ using the FOIL Method.

Apply the distributive property.

$x = 2 \sqrt{\frac{10 (10 + 2 \sqrt{21}) - 2 \sqrt{21} (10 + 2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Apply the distributive property.

$x = 2 \sqrt{\frac{10 \cdot 10 + 10 (2 \sqrt{21}) - 2 \sqrt{21} (10 + 2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Apply the distributive property.

$x = 2 \sqrt{\frac{10 \cdot 10 + 10 (2 \sqrt{21}) - 2 \sqrt{21} \cdot 10 - 2 \sqrt{21} (2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{10 \cdot 10 + 10 (2 \sqrt{21}) - 2 \sqrt{21} \cdot 10 - 2 \sqrt{21} (2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify and combine like terms.

Simplify each term.

Multiply $10$ by $10$ .

$x = 2 \sqrt{\frac{100 + 10 (2 \sqrt{21}) - 2 \sqrt{21} \cdot 10 - 2 \sqrt{21} (2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $2$ by $10$ .

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 2 \sqrt{21} \cdot 10 - 2 \sqrt{21} (2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $10$ by $- 2$ .

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 2 \sqrt{21} (2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $- 2 \sqrt{21} (2 \sqrt{21})$ .

Multiply $2$ by $- 2$ .

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \sqrt{21} \sqrt{21}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Raise $\sqrt{21}$ to the power of $1$ .

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 (\sqrt{21} \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Raise $\sqrt{21}$ to the power of $1$ .

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 (\sqrt{21} \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 {\sqrt{21}}^{1 + 1}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Add $1$ and $1$ .

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 {\sqrt{21}}^{2}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 {\sqrt{21}}^{2}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Rewrite ${\sqrt{21}}^{2}$ as $21$ .

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{21}$ as $21^{\frac{1}{2}}$ .

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 {(21^{\frac{1}{2}})}^{2}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \cdot 21^{\frac{1}{2} \cdot 2}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Combine $\frac{1}{2}$ and $2$ .

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \cdot 21^{\frac{2}{2}}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Cancel the common factor of $2$ .

Cancel the common factor.

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \cdot 21^{\frac{2}{2}}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Rewrite the expression.

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Evaluate the exponent.

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $- 4$ by $21$ .

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 84}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 84}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Subtract $84$ from $100$ .

$x = 2 \sqrt{\frac{16 + 20 \sqrt{21} - 20 \sqrt{21}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Subtract $20 \sqrt{21}$ from $20 \sqrt{21}$ .

$x = 2 \sqrt{\frac{16 + 0}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Add $16$ and $0$ .

$x = 2 \sqrt{\frac{16}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{16}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 \sqrt{\frac{16}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $5$ by $5$ .

$x = 2 \sqrt{\frac{16}{25}}$

$y = - \frac{2 \sqrt{21}}{5}$

Rewrite $\sqrt{\frac{16}{25}}$ as $\frac{\sqrt{16}}{\sqrt{25}}$ .

$x = 2 (\frac{\sqrt{16}}{\sqrt{25}})$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify the numerator.

Rewrite $16$ as $4^{2}$ .

$x = 2 (\frac{\sqrt{4^{2}}}{\sqrt{25}})$

$y = - \frac{2 \sqrt{21}}{5}$

Pull terms out from under the radical, assuming positive real numbers.

$x = 2 (\frac{4}{\sqrt{25}})$

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 (\frac{4}{\sqrt{25}})$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify the denominator.

Rewrite $25$ as $5^{2}$ .

$x = 2 (\frac{4}{\sqrt{5^{2}}})$

$y = - \frac{2 \sqrt{21}}{5}$

Pull terms out from under the radical, assuming positive real numbers.

$x = 2 (\frac{4}{5})$

$y = - \frac{2 \sqrt{21}}{5}$

$x = 2 (\frac{4}{5})$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $2 (\frac{4}{5})$ .

Combine $2$ and $\frac{4}{5}$ .

$x = \frac{2 \cdot 4}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $2$ by $4$ .

$x = \frac{8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = \frac{8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = \frac{8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = \frac{8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = \frac{8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = \frac{8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = \frac{8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

Step 3

Solve the system $x = - 2 \sqrt{(2 + y) (2 - y)}, 6 x^{2} - y^{2} = 12$ .

Replace all occurrences of $x$ with $- 2 \sqrt{(2 + y) (2 - y)}$ in each equation.

Replace all occurrences of $x$ in $6 x^{2} - y^{2} = 12$ with $- 2 \sqrt{(2 + y) (2 - y)}$ .

$6 {(- 2 \sqrt{(2 + y) (2 - y)})}^{2} - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Simplify the left side.

Simplify $6 {(- 2 \sqrt{(2 + y) (2 - y)})}^{2} - y^{2}$ .

Simplify each term.

Apply the product rule to $- 2 \sqrt{(2 + y) (2 - y)}$ .

$6 ({(- 2)}^{2} {\sqrt{(2 + y) (2 - y)}}^{2}) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Raise $- 2$ to the power of $2$ .

$6 (4 {\sqrt{(2 + y) (2 - y)}}^{2}) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Rewrite ${\sqrt{(2 + y) (2 - y)}}^{2}$ as $(2 + y) (2 - y)$ .

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{(2 + y) (2 - y)}$ as ${((2 + y) (2 - y))}^{\frac{1}{2}}$ .

$6 (4 {({((2 + y) (2 - y))}^{\frac{1}{2}})}^{2}) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$6 (4 {((2 + y) (2 - y))}^{\frac{1}{2} \cdot 2}) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Combine $\frac{1}{2}$ and $2$ .

$6 (4 {((2 + y) (2 - y))}^{\frac{2}{2}}) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Cancel the common factor of $2$ .

Cancel the common factor.

$6 (4 {((2 + y) (2 - y))}^{\frac{2}{2}}) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Rewrite the expression.

$6 (4 ((2 + y) (2 - y))) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$6 (4 ((2 + y) (2 - y))) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Simplify.

$6 (4 ((2 + y) (2 - y))) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$6 (4 ((2 + y) (2 - y))) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Expand $(2 + y) (2 - y)$ using the FOIL Method.

Apply the distributive property.

$6 (4 (2 (2 - y) + y (2 - y))) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Apply the distributive property.

$6 (4 (2 \cdot 2 + 2 (- y) + y (2 - y))) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Apply the distributive property.

$6 (4 (2 \cdot 2 + 2 (- y) + y \cdot 2 + y (- y))) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$6 (4 (2 \cdot 2 + 2 (- y) + y \cdot 2 + y (- y))) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Simplify and combine like terms.

Simplify each term.

Multiply $2$ by $2$ .

$6 (4 (4 + 2 (- y) + y \cdot 2 + y (- y))) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Multiply $- 1$ by $2$ .

$6 (4 (4 - 2 y + y \cdot 2 + y (- y))) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Move $2$ to the left of $y$ .

$6 (4 (4 - 2 y + 2 \cdot y + y (- y))) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Rewrite using the commutative property of multiplication.

$6 (4 (4 - 2 y + 2 y - y \cdot y)) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Multiply $y$ by $y$ by adding the exponents.

Move $y$ .

$6 (4 (4 - 2 y + 2 y - (y \cdot y))) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Multiply $y$ by $y$ .

$6 (4 (4 - 2 y + 2 y - y^{2})) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$6 (4 (4 - 2 y + 2 y - y^{2})) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$6 (4 (4 - 2 y + 2 y - y^{2})) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Add $- 2 y$ and $2 y$ .

$6 (4 (4 + 0 - y^{2})) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Add $4$ and $0$ .

$6 (4 (4 - y^{2})) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$6 (4 (4 - y^{2})) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Apply the distributive property.

$6 (4 \cdot 4 + 4 (- y^{2})) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Multiply $4$ by $4$ .

$6 (16 + 4 (- y^{2})) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Multiply $- 1$ by $4$ .

$6 (16 - 4 y^{2}) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Apply the distributive property.

$6 \cdot 16 + 6 (- 4 y^{2}) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Multiply $6$ by $16$ .

$96 + 6 (- 4 y^{2}) - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Multiply $- 4$ by $6$ .

$96 - 24 y^{2} - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$96 - 24 y^{2} - y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Subtract $y^{2}$ from $- 24 y^{2}$ .

$96 - 25 y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$96 - 25 y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$96 - 25 y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$96 - 25 y^{2} = 12$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Solve for $y$ in $96 - 25 y^{2} = 12$ .

Move all terms not containing $y$ to the right side of the equation.

Subtract $96$ from both sides of the equation.

$- 25 y^{2} = 12 - 96$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Subtract $96$ from $12$ .

$- 25 y^{2} = - 84$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$- 25 y^{2} = - 84$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Divide each term in $- 25 y^{2} = - 84$ by $- 25$ and simplify.

Divide each term in $- 25 y^{2} = - 84$ by $- 25$ .

$\frac{- 25 y^{2}}{- 25} = \frac{- 84}{- 25}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Simplify the left side.

Cancel the common factor of $- 25$ .

Cancel the common factor.

$\frac{- 25 y^{2}}{- 25} = \frac{- 84}{- 25}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Divide $y^{2}$ by $1$ .

$y^{2} = \frac{- 84}{- 25}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$y^{2} = \frac{- 84}{- 25}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$y^{2} = \frac{- 84}{- 25}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Simplify the right side.

Dividing two negative values results in a positive value.

$y^{2} = \frac{84}{25}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$y^{2} = \frac{84}{25}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$y^{2} = \frac{84}{25}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Take the specified root of both sides of the equation to eliminate the exponent on the left side.

$y = \pm \sqrt{\frac{84}{25}}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Simplify $\pm \sqrt{\frac{84}{25}}$ .

Rewrite $\sqrt{\frac{84}{25}}$ as $\frac{\sqrt{84}}{\sqrt{25}}$ .

$y = \pm \frac{\sqrt{84}}{\sqrt{25}}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Simplify the numerator.

Rewrite $84$ as $2^{2} \cdot 21$ .

Factor $4$ out of $84$ .

$y = \pm \frac{\sqrt{4 (21)}}{\sqrt{25}}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Rewrite $4$ as $2^{2}$ .

$y = \pm \frac{\sqrt{2^{2} \cdot 21}}{\sqrt{25}}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$y = \pm \frac{\sqrt{2^{2} \cdot 21}}{\sqrt{25}}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Pull terms out from under the radical.

$y = \pm \frac{2 \sqrt{21}}{\sqrt{25}}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$y = \pm \frac{2 \sqrt{21}}{\sqrt{25}}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Simplify the denominator.

Rewrite $25$ as $5^{2}$ .

$y = \pm \frac{2 \sqrt{21}}{\sqrt{5^{2}}}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Pull terms out from under the radical, assuming positive real numbers.

$y = \pm \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$y = \pm \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$y = \pm \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

The complete solution is the result of both the positive and negative portions of the solution.

First, use the positive value of the $\pm$ to find the first solution.

$y = \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Next, use the negative value of the $\pm$ to find the second solution.

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

The complete solution is the result of both the positive and negative portions of the solution.

$y = \frac{2 \sqrt{21}}{5}, - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$y = \frac{2 \sqrt{21}}{5}, - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

$y = \frac{2 \sqrt{21}}{5}, - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{(2 + y) (2 - y)}$

Replace all occurrences of $y$ with $\frac{2 \sqrt{21}}{5}$ in each equation.

Replace all occurrences of $y$ in $x = - 2 \sqrt{(2 + y) (2 - y)}$ with $\frac{2 \sqrt{21}}{5}$ .

$x = - 2 \sqrt{(2 + \frac{2 \sqrt{21}}{5}) (2 - (\frac{2 \sqrt{21}}{5}))}$

$y = \frac{2 \sqrt{21}}{5}$

Simplify $x = - 2 \sqrt{(2 + \frac{2 \sqrt{21}}{5}) (2 - (\frac{2 \sqrt{21}}{5}))}$ .

Simplify the left side.

Remove parentheses.

$x = - 2 \sqrt{(2 + \frac{2 \sqrt{21}}{5}) (2 - (\frac{2 \sqrt{21}}{5}))}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{(2 + \frac{2 \sqrt{21}}{5}) (2 - (\frac{2 \sqrt{21}}{5}))}$

$y = \frac{2 \sqrt{21}}{5}$

Simplify the right side.

Simplify $- 2 \sqrt{(2 + \frac{2 \sqrt{21}}{5}) (2 - (\frac{2 \sqrt{21}}{5}))}$ .

To write $2$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$x = - 2 \sqrt{(2 \cdot \frac{5}{5} + \frac{2 \sqrt{21}}{5}) (2 - \frac{2 \sqrt{21}}{5})}$

$y = \frac{2 \sqrt{21}}{5}$

Combine $2$ and $\frac{5}{5}$ .

$x = - 2 \sqrt{(\frac{2 \cdot 5}{5} + \frac{2 \sqrt{21}}{5}) (2 - \frac{2 \sqrt{21}}{5})}$

$y = \frac{2 \sqrt{21}}{5}$

Simplify the expression.

Combine the numerators over the common denominator.

$x = - 2 \sqrt{\frac{2 \cdot 5 + 2 \sqrt{21}}{5} \cdot (2 - \frac{2 \sqrt{21}}{5})}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $2$ by $5$ .

$x = - 2 \sqrt{\frac{10 + 2 \sqrt{21}}{5} \cdot (2 - \frac{2 \sqrt{21}}{5})}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{10 + 2 \sqrt{21}}{5} \cdot (2 - \frac{2 \sqrt{21}}{5})}$

$y = \frac{2 \sqrt{21}}{5}$

To write $2$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$x = - 2 \sqrt{\frac{10 + 2 \sqrt{21}}{5} \cdot (2 \cdot \frac{5}{5} - \frac{2 \sqrt{21}}{5})}$

$y = \frac{2 \sqrt{21}}{5}$

Combine fractions.

Combine $2$ and $\frac{5}{5}$ .

$x = - 2 \sqrt{\frac{10 + 2 \sqrt{21}}{5} \cdot (\frac{2 \cdot 5}{5} - \frac{2 \sqrt{21}}{5})}$

$y = \frac{2 \sqrt{21}}{5}$

Simplify the expression.

Combine the numerators over the common denominator.

$x = - 2 \sqrt{\frac{10 + 2 \sqrt{21}}{5} \cdot \frac{2 \cdot 5 - 2 \sqrt{21}}{5}}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $2$ by $5$ .

$x = - 2 \sqrt{\frac{10 + 2 \sqrt{21}}{5} \cdot \frac{10 - 2 \sqrt{21}}{5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{10 + 2 \sqrt{21}}{5} \cdot \frac{10 - 2 \sqrt{21}}{5}}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $\frac{10 + 2 \sqrt{21}}{5}$ by $\frac{10 - 2 \sqrt{21}}{5}$ .

$x = - 2 \sqrt{\frac{(10 + 2 \sqrt{21}) (10 - 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{(10 + 2 \sqrt{21}) (10 - 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Simplify the numerator.

Expand $(10 + 2 \sqrt{21}) (10 - 2 \sqrt{21})$ using the FOIL Method.

Apply the distributive property.

$x = - 2 \sqrt{\frac{10 (10 - 2 \sqrt{21}) + 2 \sqrt{21} (10 - 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Apply the distributive property.

$x = - 2 \sqrt{\frac{10 \cdot 10 + 10 (- 2 \sqrt{21}) + 2 \sqrt{21} (10 - 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Apply the distributive property.

$x = - 2 \sqrt{\frac{10 \cdot 10 + 10 (- 2 \sqrt{21}) + 2 \sqrt{21} \cdot 10 + 2 \sqrt{21} (- 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{10 \cdot 10 + 10 (- 2 \sqrt{21}) + 2 \sqrt{21} \cdot 10 + 2 \sqrt{21} (- 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Simplify and combine like terms.

Simplify each term.

Multiply $10$ by $10$ .

$x = - 2 \sqrt{\frac{100 + 10 (- 2 \sqrt{21}) + 2 \sqrt{21} \cdot 10 + 2 \sqrt{21} (- 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $- 2$ by $10$ .

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 2 \sqrt{21} \cdot 10 + 2 \sqrt{21} (- 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $10$ by $2$ .

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} + 2 \sqrt{21} (- 2 \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $2 \sqrt{21} (- 2 \sqrt{21})$ .

Multiply $- 2$ by $2$ .

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \sqrt{21} \sqrt{21}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Raise $\sqrt{21}$ to the power of $1$ .

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 (\sqrt{21} \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Raise $\sqrt{21}$ to the power of $1$ .

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 (\sqrt{21} \sqrt{21})}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 {\sqrt{21}}^{1 + 1}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Add $1$ and $1$ .

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 {\sqrt{21}}^{2}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 {\sqrt{21}}^{2}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Rewrite ${\sqrt{21}}^{2}$ as $21$ .

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{21}$ as $21^{\frac{1}{2}}$ .

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 {(21^{\frac{1}{2}})}^{2}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \cdot 21^{\frac{1}{2} \cdot 2}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Combine $\frac{1}{2}$ and $2$ .

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \cdot 21^{\frac{2}{2}}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Cancel the common factor of $2$ .

Cancel the common factor.

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \cdot 21^{\frac{2}{2}}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Rewrite the expression.

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Evaluate the exponent.

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $- 4$ by $21$ .

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 84}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{100 - 20 \sqrt{21} + 20 \sqrt{21} - 84}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Subtract $84$ from $100$ .

$x = - 2 \sqrt{\frac{16 - 20 \sqrt{21} + 20 \sqrt{21}}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Add $- 20 \sqrt{21}$ and $20 \sqrt{21}$ .

$x = - 2 \sqrt{\frac{16 + 0}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Add $16$ and $0$ .

$x = - 2 \sqrt{\frac{16}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{16}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{16}{5 \cdot 5}}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $5$ by $5$ .

$x = - 2 \sqrt{\frac{16}{25}}$

$y = \frac{2 \sqrt{21}}{5}$

Rewrite $\sqrt{\frac{16}{25}}$ as $\frac{\sqrt{16}}{\sqrt{25}}$ .

$x = - 2 \frac{\sqrt{16}}{\sqrt{25}}$

$y = \frac{2 \sqrt{21}}{5}$

Simplify the numerator.

Rewrite $16$ as $4^{2}$ .

$x = - 2 \frac{\sqrt{4^{2}}}{\sqrt{25}}$

$y = \frac{2 \sqrt{21}}{5}$

Pull terms out from under the radical, assuming positive real numbers.

$x = - 2 \frac{4}{\sqrt{25}}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - 2 \frac{4}{\sqrt{25}}$

$y = \frac{2 \sqrt{21}}{5}$

Simplify the denominator.

Rewrite $25$ as $5^{2}$ .

$x = - 2 \frac{4}{\sqrt{5^{2}}}$

$y = \frac{2 \sqrt{21}}{5}$

Pull terms out from under the radical, assuming positive real numbers.

$x = - 2 (\frac{4}{5})$

$y = \frac{2 \sqrt{21}}{5}$

$x = - 2 (\frac{4}{5})$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $- 2 (\frac{4}{5})$ .

Combine $- 2$ and $\frac{4}{5}$ .

$x = \frac{- 2 \cdot 4}{5}$

$y = \frac{2 \sqrt{21}}{5}$

Multiply $- 2$ by $4$ .

$x = \frac{- 8}{5}$

$y = \frac{2 \sqrt{21}}{5}$

$x = \frac{- 8}{5}$

$y = \frac{2 \sqrt{21}}{5}$

Move the negative in front of the fraction.

$x = - \frac{8}{5}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - \frac{8}{5}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - \frac{8}{5}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - \frac{8}{5}$

$y = \frac{2 \sqrt{21}}{5}$

$x = - \frac{8}{5}$

$y = \frac{2 \sqrt{21}}{5}$

Replace all occurrences of $y$ with $- \frac{2 \sqrt{21}}{5}$ in each equation.

Replace all occurrences of $y$ in $x = - 2 \sqrt{(2 + y) (2 - y)}$ with $- \frac{2 \sqrt{21}}{5}$ .

$x = - 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 - (- \frac{2 \sqrt{21}}{5}))}$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify $x = - 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 - (- \frac{2 \sqrt{21}}{5}))}$ .

Simplify the left side.

Remove parentheses.

$x = - 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 - (- \frac{2 \sqrt{21}}{5}))}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 - (- \frac{2 \sqrt{21}}{5}))}$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify the right side.

Simplify $- 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 - (- \frac{2 \sqrt{21}}{5}))}$ .

Multiply $- - \frac{2 \sqrt{21}}{5}$ .

Multiply $- 1$ by $- 1$ .

$x = - 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 + 1 (\frac{2 \sqrt{21}}{5}))}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $\frac{2 \sqrt{21}}{5}$ by $1$ .

$x = - 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{(2 - \frac{2 \sqrt{21}}{5}) (2 + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

To write $2$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$x = - 2 \sqrt{(2 \cdot \frac{5}{5} - \frac{2 \sqrt{21}}{5}) (2 + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

Combine $2$ and $\frac{5}{5}$ .

$x = - 2 \sqrt{(\frac{2 \cdot 5}{5} - \frac{2 \sqrt{21}}{5}) (2 + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify the expression.

Combine the numerators over the common denominator.

$x = - 2 \sqrt{\frac{2 \cdot 5 - 2 \sqrt{21}}{5} \cdot (2 + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $2$ by $5$ .

$x = - 2 \sqrt{\frac{10 - 2 \sqrt{21}}{5} \cdot (2 + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{10 - 2 \sqrt{21}}{5} \cdot (2 + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

To write $2$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$x = - 2 \sqrt{\frac{10 - 2 \sqrt{21}}{5} \cdot (2 \cdot \frac{5}{5} + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

Combine fractions.

Combine $2$ and $\frac{5}{5}$ .

$x = - 2 \sqrt{\frac{10 - 2 \sqrt{21}}{5} \cdot (\frac{2 \cdot 5}{5} + \frac{2 \sqrt{21}}{5})}$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify the expression.

Combine the numerators over the common denominator.

$x = - 2 \sqrt{\frac{10 - 2 \sqrt{21}}{5} \cdot \frac{2 \cdot 5 + 2 \sqrt{21}}{5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $2$ by $5$ .

$x = - 2 \sqrt{\frac{10 - 2 \sqrt{21}}{5} \cdot \frac{10 + 2 \sqrt{21}}{5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{10 - 2 \sqrt{21}}{5} \cdot \frac{10 + 2 \sqrt{21}}{5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $\frac{10 - 2 \sqrt{21}}{5}$ by $\frac{10 + 2 \sqrt{21}}{5}$ .

$x = - 2 \sqrt{\frac{(10 - 2 \sqrt{21}) (10 + 2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{(10 - 2 \sqrt{21}) (10 + 2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify the numerator.

Expand $(10 - 2 \sqrt{21}) (10 + 2 \sqrt{21})$ using the FOIL Method.

Apply the distributive property.

$x = - 2 \sqrt{\frac{10 (10 + 2 \sqrt{21}) - 2 \sqrt{21} (10 + 2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Apply the distributive property.

$x = - 2 \sqrt{\frac{10 \cdot 10 + 10 (2 \sqrt{21}) - 2 \sqrt{21} (10 + 2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Apply the distributive property.

$x = - 2 \sqrt{\frac{10 \cdot 10 + 10 (2 \sqrt{21}) - 2 \sqrt{21} \cdot 10 - 2 \sqrt{21} (2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{10 \cdot 10 + 10 (2 \sqrt{21}) - 2 \sqrt{21} \cdot 10 - 2 \sqrt{21} (2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify and combine like terms.

Simplify each term.

Multiply $10$ by $10$ .

$x = - 2 \sqrt{\frac{100 + 10 (2 \sqrt{21}) - 2 \sqrt{21} \cdot 10 - 2 \sqrt{21} (2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $2$ by $10$ .

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 2 \sqrt{21} \cdot 10 - 2 \sqrt{21} (2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $10$ by $- 2$ .

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 2 \sqrt{21} (2 \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $- 2 \sqrt{21} (2 \sqrt{21})$ .

Multiply $2$ by $- 2$ .

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \sqrt{21} \sqrt{21}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Raise $\sqrt{21}$ to the power of $1$ .

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 (\sqrt{21} \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Raise $\sqrt{21}$ to the power of $1$ .

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 (\sqrt{21} \sqrt{21})}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 {\sqrt{21}}^{1 + 1}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Add $1$ and $1$ .

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 {\sqrt{21}}^{2}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 {\sqrt{21}}^{2}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Rewrite ${\sqrt{21}}^{2}$ as $21$ .

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{21}$ as $21^{\frac{1}{2}}$ .

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 {(21^{\frac{1}{2}})}^{2}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \cdot 21^{\frac{1}{2} \cdot 2}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Combine $\frac{1}{2}$ and $2$ .

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \cdot 21^{\frac{2}{2}}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Cancel the common factor of $2$ .

Cancel the common factor.

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \cdot 21^{\frac{2}{2}}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Rewrite the expression.

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Evaluate the exponent.

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 4 \cdot 21}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $- 4$ by $21$ .

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 84}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{100 + 20 \sqrt{21} - 20 \sqrt{21} - 84}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Subtract $84$ from $100$ .

$x = - 2 \sqrt{\frac{16 + 20 \sqrt{21} - 20 \sqrt{21}}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Subtract $20 \sqrt{21}$ from $20 \sqrt{21}$ .

$x = - 2 \sqrt{\frac{16 + 0}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Add $16$ and $0$ .

$x = - 2 \sqrt{\frac{16}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{16}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 \sqrt{\frac{16}{5 \cdot 5}}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $5$ by $5$ .

$x = - 2 \sqrt{\frac{16}{25}}$

$y = - \frac{2 \sqrt{21}}{5}$

Rewrite $\sqrt{\frac{16}{25}}$ as $\frac{\sqrt{16}}{\sqrt{25}}$ .

$x = - 2 \frac{\sqrt{16}}{\sqrt{25}}$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify the numerator.

Rewrite $16$ as $4^{2}$ .

$x = - 2 \frac{\sqrt{4^{2}}}{\sqrt{25}}$

$y = - \frac{2 \sqrt{21}}{5}$

Pull terms out from under the radical, assuming positive real numbers.

$x = - 2 \frac{4}{\sqrt{25}}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 \frac{4}{\sqrt{25}}$

$y = - \frac{2 \sqrt{21}}{5}$

Simplify the denominator.

Rewrite $25$ as $5^{2}$ .

$x = - 2 \frac{4}{\sqrt{5^{2}}}$

$y = - \frac{2 \sqrt{21}}{5}$

Pull terms out from under the radical, assuming positive real numbers.

$x = - 2 (\frac{4}{5})$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - 2 (\frac{4}{5})$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $- 2 (\frac{4}{5})$ .

Combine $- 2$ and $\frac{4}{5}$ .

$x = \frac{- 2 \cdot 4}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

Multiply $- 2$ by $4$ .

$x = \frac{- 8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = \frac{- 8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

Move the negative in front of the fraction.

$x = - \frac{8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - \frac{8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - \frac{8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - \frac{8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - \frac{8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

$x = - \frac{8}{5}$

$y = - \frac{2 \sqrt{21}}{5}$

Step 4

The solution to the system is the complete set of ordered pairs that are valid solutions.

$(\frac{8}{5}, \frac{2 \sqrt{21}}{5})$

$(\frac{8}{5}, - \frac{2 \sqrt{21}}{5})$

$(- \frac{8}{5}, \frac{2 \sqrt{21}}{5})$

$(- \frac{8}{5}, - \frac{2 \sqrt{21}}{5})$

Step 5

The result can be shown in multiple forms.

Point Form:

$(\frac{8}{5}, \frac{2 \sqrt{21}}{5}), (\frac{8}{5}, - \frac{2 \sqrt{21}}{5}), (- \frac{8}{5}, \frac{2 \sqrt{21}}{5}), (- \frac{8}{5}, - \frac{2 \sqrt{21}}{5})$

Equation Form:

$x = \frac{8}{5}, y = \frac{2 \sqrt{21}}{5}$

$x = \frac{8}{5}, y = - \frac{2 \sqrt{21}}{5}$

$x = - \frac{8}{5}, y = \frac{2 \sqrt{21}}{5}$

$x = - \frac{8}{5}, y = - \frac{2 \sqrt{21}}{5}$

Step 6

Solve by Substitution x^2+4y^2=16 , 6x^2-y^2=12

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