Find the Roots (Zeros) 2x^5-2x^4-6x^3+6x^2-8x+8=0

$2 x^{5} - 2 x^{4} - 6 x^{3} + 6 x^{2} - 8 x + 8 = 0$

Step 1

Factor the left side of the equation.

Factor $2$ out of $2 x^{5} - 2 x^{4} - 6 x^{3} + 6 x^{2} - 8 x + 8$ .

Factor $2$ out of $2 x^{5}$ .

$2 (x^{5}) - 2 x^{4} - 6 x^{3} + 6 x^{2} - 8 x + 8 = 0$

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

$2 (x^{5}) + 2 (- x^{4}) - 6 x^{3} + 6 x^{2} - 8 x + 8 = 0$

Factor $2$ out of $- 6 x^{3}$ .

$2 (x^{5}) + 2 (- x^{4}) + 2 (- 3 x^{3}) + 6 x^{2} - 8 x + 8 = 0$

Factor $2$ out of $6 x^{2}$ .

$2 (x^{5}) + 2 (- x^{4}) + 2 (- 3 x^{3}) + 2 (3 x^{2}) - 8 x + 8 = 0$

Factor $2$ out of $- 8 x$ .

$2 (x^{5}) + 2 (- x^{4}) + 2 (- 3 x^{3}) + 2 (3 x^{2}) + 2 (- 4 x) + 8 = 0$

Factor $2$ out of $8$ .

$2 (x^{5}) + 2 (- x^{4}) + 2 (- 3 x^{3}) + 2 (3 x^{2}) + 2 (- 4 x) + 2 (4) = 0$

Factor $2$ out of $2 (x^{5}) + 2 (- x^{4})$ .

$2 (x^{5} - x^{4}) + 2 (- 3 x^{3}) + 2 (3 x^{2}) + 2 (- 4 x) + 2 (4) = 0$

Factor $2$ out of $2 (x^{5} - x^{4}) + 2 (- 3 x^{3})$ .

$2 (x^{5} - x^{4} - 3 x^{3}) + 2 (3 x^{2}) + 2 (- 4 x) + 2 (4) = 0$

Factor $2$ out of $2 (x^{5} - x^{4} - 3 x^{3}) + 2 (3 x^{2})$ .

$2 (x^{5} - x^{4} - 3 x^{3} + 3 x^{2}) + 2 (- 4 x) + 2 (4) = 0$

Factor $2$ out of $2 (x^{5} - x^{4} - 3 x^{3} + 3 x^{2}) + 2 (- 4 x)$ .

$2 (x^{5} - x^{4} - 3 x^{3} + 3 x^{2} - 4 x) + 2 (4) = 0$

Factor $2$ out of $2 (x^{5} - x^{4} - 3 x^{3} + 3 x^{2} - 4 x) + 2 (4)$ .

$2 (x^{5} - x^{4} - 3 x^{3} + 3 x^{2} - 4 x + 4) = 0$

Regroup terms.

$2 (x^{5} - 3 x^{3} - 4 x - x^{4} + 3 x^{2} + 4) = 0$

Factor $x$ out of $x^{5} - 3 x^{3} - 4 x$ .

Factor $x$ out of $x^{5}$ .

$2 (x \cdot x^{4} - 3 x^{3} - 4 x - x^{4} + 3 x^{2} + 4) = 0$

Factor $x$ out of $- 3 x^{3}$ .

$2 (x \cdot x^{4} + x (- 3 x^{2}) - 4 x - x^{4} + 3 x^{2} + 4) = 0$

Factor $x$ out of $- 4 x$ .

$2 (x \cdot x^{4} + x (- 3 x^{2}) + x \cdot - 4 - x^{4} + 3 x^{2} + 4) = 0$

Factor $x$ out of $x \cdot x^{4} + x (- 3 x^{2})$ .

$2 (x (x^{4} - 3 x^{2}) + x \cdot - 4 - x^{4} + 3 x^{2} + 4) = 0$

Factor $x$ out of $x (x^{4} - 3 x^{2}) + x \cdot - 4$ .

$2 (x (x^{4} - 3 x^{2} - 4) - x^{4} + 3 x^{2} + 4) = 0$

Rewrite $x^{4}$ as ${(x^{2})}^{2}$ .

$2 (x ({(x^{2})}^{2} - 3 x^{2} - 4) - x^{4} + 3 x^{2} + 4) = 0$

Let $u = x^{2}$ . Substitute $u$ for all occurrences of $x^{2}$ .

$2 (x (u^{2} - 3 u - 4) - x^{4} + 3 x^{2} + 4) = 0$

Factor $u^{2} - 3 u - 4$ using the AC method.

Consider the form $x^{2} + b x + c$ . Find a pair of integers whose product is $c$ and whose sum is $b$ . In this case, whose product is $- 4$ and whose sum is $- 3$ .

$- 4, 1$

Write the factored form using these integers.

$2 (x ((u - 4) (u + 1)) - x^{4} + 3 x^{2} + 4) = 0$

Replace all occurrences of $u$ with $x^{2}$ .

$2 (x ((x^{2} - 4) (x^{2} + 1)) - x^{4} + 3 x^{2} + 4) = 0$

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

$2 (x ((x^{2} - 2^{2}) (x^{2} + 1)) - x^{4} + 3 x^{2} + 4) = 0$

Factor.

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

$2 (x ((x + 2) (x - 2) (x^{2} + 1)) - x^{4} + 3 x^{2} + 4) = 0$

Remove unnecessary parentheses.

$2 (x (x + 2) (x - 2) (x^{2} + 1) - x^{4} + 3 x^{2} + 4) = 0$

Rewrite $x^{4}$ as ${(x^{2})}^{2}$ .

$2 (x (x + 2) (x - 2) (x^{2} + 1) - {(x^{2})}^{2} + 3 x^{2} + 4) = 0$

Let $u = x^{2}$ . Substitute $u$ for all occurrences of $x^{2}$ .

$2 (x (x + 2) (x - 2) (x^{2} + 1) - u^{2} + 3 u + 4) = 0$

Factor by grouping.

For a polynomial of the form $a x^{2} + b x + c$ , rewrite the middle term as a sum of two terms whose product is $a \cdot c = - 1 \cdot 4 = - 4$ and whose sum is $b = 3$ .

Factor $3$ out of $3 u$ .

$2 (x (x + 2) (x - 2) (x^{2} + 1) - u^{2} + 3 (u) + 4) = 0$

Rewrite $3$ as $- 1$ plus $4$

$2 (x (x + 2) (x - 2) (x^{2} + 1) - u^{2} + (- 1 + 4) u + 4) = 0$

Apply the distributive property.

$2 (x (x + 2) (x - 2) (x^{2} + 1) - u^{2} - 1 u + 4 u + 4) = 0$

Factor out the greatest common factor from each group.

Group the first two terms and the last two terms.

$2 (x (x + 2) (x - 2) (x^{2} + 1) - u^{2} - 1 u + 4 u + 4) = 0$

Factor out the greatest common factor (GCF) from each group.

$2 (x (x + 2) (x - 2) (x^{2} + 1) + u (- u - 1) - 4 (- u - 1)) = 0$

Factor the polynomial by factoring out the greatest common factor, $- u - 1$ .

$2 (x (x + 2) (x - 2) (x^{2} + 1) + (- u - 1) (u - 4)) = 0$

Replace all occurrences of $u$ with $x^{2}$ .

$2 (x (x + 2) (x - 2) (x^{2} + 1) + (- x^{2} - 1) (x^{2} - 4)) = 0$

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

$2 (x (x + 2) (x - 2) (x^{2} + 1) + (- x^{2} - 1) (x^{2} - 2^{2})) = 0$

Factor.

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

$2 (x (x + 2) (x - 2) (x^{2} + 1) + (- x^{2} - 1) ((x + 2) (x - 2))) = 0$

Remove unnecessary parentheses.

$2 (x (x + 2) (x - 2) (x^{2} + 1) + (- x^{2} - 1) (x + 2) (x - 2)) = 0$

Factor $(x + 2) (x - 2)$ out of $x (x + 2) (x - 2) (x^{2} + 1) + (- x^{2} - 1) (x + 2) (x - 2)$ .

Factor $(x + 2) (x - 2)$ out of $x (x + 2) (x - 2) (x^{2} + 1)$ .

$2 ((x + 2) (x - 2) ((x) (x^{2} + 1)) + (- x^{2} - 1) (x + 2) (x - 2)) = 0$

Factor $(x + 2) (x - 2)$ out of $(- x^{2} - 1) (x + 2) (x - 2)$ .

$2 ((x + 2) (x - 2) ((x) (x^{2} + 1)) + (x + 2) (x - 2) (- x^{2} - 1)) = 0$

Factor $(x + 2) (x - 2)$ out of $(x + 2) (x - 2) ((x) (x^{2} + 1)) + (x + 2) (x - 2) (- x^{2} - 1)$ .

$2 ((x + 2) (x - 2) ((x) (x^{2} + 1) - x^{2} - 1)) = 0$

Apply the distributive property.

$2 ((x + 2) (x - 2) (x \cdot x^{2} + x \cdot 1 - x^{2} - 1)) = 0$

Multiply $x$ by $x^{2}$ by adding the exponents.

Multiply $x$ by $x^{2}$ .

Raise $x$ to the power of $1$ .

$2 ((x + 2) (x - 2) (x \cdot x^{2} + x \cdot 1 - x^{2} - 1)) = 0$

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

$2 ((x + 2) (x - 2) (x^{1 + 2} + x \cdot 1 - x^{2} - 1)) = 0$

Add $1$ and $2$ .

$2 ((x + 2) (x - 2) (x^{3} + x \cdot 1 - x^{2} - 1)) = 0$

Multiply $x$ by $1$ .

$2 ((x + 2) (x - 2) (x^{3} + x - x^{2} - 1)) = 0$

Reorder terms.

$2 ((x + 2) (x - 2) (x^{3} - x^{2} + x - 1)) = 0$

Factor.

Rewrite $x^{3} - x^{2} + x - 1$ in a factored form.

Factor out the greatest common factor from each group.

Group the first two terms and the last two terms.

$2 ((x + 2) (x - 2) ((x^{3} - x^{2}) + x - 1)) = 0$

Factor out the greatest common factor (GCF) from each group.

$2 ((x + 2) (x - 2) (x^{2} (x - 1) + 1 (x - 1))) = 0$

Factor the polynomial by factoring out the greatest common factor, $x - 1$ .

$2 ((x + 2) (x - 2) ((x - 1) (x^{2} + 1))) = 0$

Remove unnecessary parentheses.

$2 ((x + 2) (x - 2) (x - 1) (x^{2} + 1)) = 0$

Remove unnecessary parentheses.

$2 (x + 2) (x - 2) (x - 1) (x^{2} + 1) = 0$

Step 2

If any individual factor on the left side of the equation is equal to $0$ , the entire expression will be equal to $0$ .

$x + 2 = 0$

$x - 2 = 0$

$x - 1 = 0$

$x^{2} + 1 = 0$

Step 3

Set $x + 2$ equal to $0$ and solve for $x$ .

Set $x + 2$ equal to $0$ .

$x + 2 = 0$

Subtract $2$ from both sides of the equation.

$x = - 2$

Step 4

Set $x - 2$ equal to $0$ and solve for $x$ .

Set $x - 2$ equal to $0$ .

$x - 2 = 0$

Add $2$ to both sides of the equation.

$x = 2$

Step 5

Set $x - 1$ equal to $0$ and solve for $x$ .

Set $x - 1$ equal to $0$ .

$x - 1 = 0$

Add $1$ to both sides of the equation.

$x = 1$

Step 6

Set $x^{2} + 1$ equal to $0$ and solve for $x$ .

Set $x^{2} + 1$ equal to $0$ .

$x^{2} + 1 = 0$

Solve $x^{2} + 1 = 0$ for $x$ .

Subtract $1$ from both sides of the equation.

$x^{2} = - 1$

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

$x = \pm \sqrt{- 1}$

Rewrite $\sqrt{- 1}$ as $i$ .

$x = \pm i$

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.

$x = i$

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

$x = - i$

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

$x = i, - i$

Step 7

The final solution is all the values that make $2 (x + 2) (x - 2) (x - 1) (x^{2} + 1) = 0$ true.

$x = - 2, 2, 1, i, - i$

Step 8

Find the Roots (Zeros) 2x^5-2x^4-6x^3+6x^2-8x+8=0

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