Find the Axis of Symmetry -8x+24=y^2+4y+4

$- 8 x + 24 = y^{2} + 4 y + 4$

Step 1

Rewrite the equation in vertex form.

Isolate $x$ to the left side of the equation.

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

Subtract $24$ from both sides of the equation.

$- 8 x = y^{2} + 4 y + 4 - 24$

Subtract $24$ from $4$ .

$- 8 x = y^{2} + 4 y - 20$

Divide each term in $- 8 x = y^{2} + 4 y - 20$ by $- 8$ and simplify.

Divide each term in $- 8 x = y^{2} + 4 y - 20$ by $- 8$ .

$\frac{- 8 x}{- 8} = \frac{y^{2}}{- 8} + \frac{4 y}{- 8} + \frac{- 20}{- 8}$

Simplify the left side.

Cancel the common factor of $- 8$ .

Cancel the common factor.

$\frac{- 8 x}{- 8} = \frac{y^{2}}{- 8} + \frac{4 y}{- 8} + \frac{- 20}{- 8}$

Divide $x$ by $1$ .

$x = \frac{y^{2}}{- 8} + \frac{4 y}{- 8} + \frac{- 20}{- 8}$

Simplify the right side.

Simplify each term.

Move the negative in front of the fraction.

$x = - \frac{y^{2}}{8} + \frac{4 y}{- 8} + \frac{- 20}{- 8}$

Cancel the common factor of $4$ and $- 8$ .

Factor $4$ out of $4 y$ .

$x = - \frac{y^{2}}{8} + \frac{4 (y)}{- 8} + \frac{- 20}{- 8}$

Cancel the common factors.

Factor $4$ out of $- 8$ .

$x = - \frac{y^{2}}{8} + \frac{4 y}{4 \cdot - 2} + \frac{- 20}{- 8}$

Cancel the common factor.

$x = - \frac{y^{2}}{8} + \frac{4 y}{4 \cdot - 2} + \frac{- 20}{- 8}$

Rewrite the expression.

$x = - \frac{y^{2}}{8} + \frac{y}{- 2} + \frac{- 20}{- 8}$

Move the negative in front of the fraction.

$x = - \frac{y^{2}}{8} - \frac{y}{2} + \frac{- 20}{- 8}$

Cancel the common factor of $- 20$ and $- 8$ .

Factor $- 4$ out of $- 20$ .

$x = - \frac{y^{2}}{8} - \frac{y}{2} + \frac{- 4 (5)}{- 8}$

Cancel the common factors.

Factor $- 4$ out of $- 8$ .

$x = - \frac{y^{2}}{8} - \frac{y}{2} + \frac{- 4 \cdot 5}{- 4 \cdot 2}$

Cancel the common factor.

$x = - \frac{y^{2}}{8} - \frac{y}{2} + \frac{- 4 \cdot 5}{- 4 \cdot 2}$

Rewrite the expression.

$x = - \frac{y^{2}}{8} - \frac{y}{2} + \frac{5}{2}$

Complete the square for $- \frac{y^{2}}{8} - \frac{y}{2} + \frac{5}{2}$ .

Use the form $a x^{2} + b x + c$ , to find the values of $a$ , $b$ , and $c$ .

$a = - \frac{1}{8}$

$b = - \frac{1}{2}$

$c = \frac{5}{2}$

Consider the vertex form of a parabola.

$a {(x + d)}^{2} + e$

Find the value of $d$ using the formula $d = \frac{b}{2 a}$ .

Substitute the values of $a$ and $b$ into the formula $d = \frac{b}{2 a}$ .

$d = \frac{- \frac{1}{2}}{2 (- \frac{1}{8})}$

Simplify the right side.

Dividing two negative values results in a positive value.

$d = \frac{\frac{1}{2}}{2 (\frac{1}{8})}$

Multiply the numerator by the reciprocal of the denominator.

$d = \frac{1}{2} \cdot \frac{1}{2 (\frac{1}{8})}$

Combine $2$ and $\frac{1}{8}$ .

$d = \frac{1}{2} \cdot \frac{1}{\frac{2}{8}}$

Cancel the common factor of $2$ and $8$ .

Factor $2$ out of $2$ .

$d = \frac{1}{2} \cdot \frac{1}{\frac{2 (1)}{8}}$

Cancel the common factors.

Factor $2$ out of $8$ .

$d = \frac{1}{2} \cdot \frac{1}{\frac{2 \cdot 1}{2 \cdot 4}}$

Cancel the common factor.

$d = \frac{1}{2} \cdot \frac{1}{\frac{2 \cdot 1}{2 \cdot 4}}$

Rewrite the expression.

$d = \frac{1}{2} \cdot \frac{1}{\frac{1}{4}}$

Multiply the numerator by the reciprocal of the denominator.

$d = \frac{1}{2} (1 \cdot 4)$

Multiply $4$ by $1$ .

$d = \frac{1}{2} \cdot 4$

Cancel the common factor of $2$ .

Factor $2$ out of $4$ .

$d = \frac{1}{2} \cdot (2 (2))$

Cancel the common factor.

$d = \frac{1}{2} \cdot (2 \cdot 2)$

Rewrite the expression.

$d = 2$

Find the value of $e$ using the formula $e = c - \frac{b^{2}}{4 a}$ .

Substitute the values of $c$ , $b$ and $a$ into the formula $e = c - \frac{b^{2}}{4 a}$ .

$e = \frac{5}{2} - \frac{{(- \frac{1}{2})}^{2}}{4 (- \frac{1}{8})}$

Simplify the right side.

Simplify each term.

Simplify the numerator.

Apply the product rule to $- \frac{1}{2}$ .

$e = \frac{5}{2} - \frac{{(- 1)}^{2} {(\frac{1}{2})}^{2}}{4 (- \frac{1}{8})}$

Raise $- 1$ to the power of $2$ .

$e = \frac{5}{2} - \frac{1 {(\frac{1}{2})}^{2}}{4 (- \frac{1}{8})}$

Apply the product rule to $\frac{1}{2}$ .

$e = \frac{5}{2} - \frac{1 \frac{1^{2}}{2^{2}}}{4 (- \frac{1}{8})}$

One to any power is one.

$e = \frac{5}{2} - \frac{1 \frac{1}{2^{2}}}{4 (- \frac{1}{8})}$

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

$e = \frac{5}{2} - \frac{1 (\frac{1}{4})}{4 (- \frac{1}{8})}$

Multiply $\frac{1}{4}$ by $1$ .

$e = \frac{5}{2} - \frac{\frac{1}{4}}{4 (- \frac{1}{8})}$

Simplify the denominator.

Multiply $- 1$ by $4$ .

$e = \frac{5}{2} - \frac{\frac{1}{4}}{- 4 (\frac{1}{8})}$

Combine $- 4$ and $\frac{1}{8}$ .

$e = \frac{5}{2} - \frac{\frac{1}{4}}{\frac{- 4}{8}}$

Reduce the expression by cancelling the common factors.

Cancel the common factor of $- 4$ and $8$ .

Factor $4$ out of $- 4$ .

$e = \frac{5}{2} - \frac{\frac{1}{4}}{\frac{4 (- 1)}{8}}$

Cancel the common factors.

Factor $4$ out of $8$ .

$e = \frac{5}{2} - \frac{\frac{1}{4}}{\frac{4 \cdot - 1}{4 \cdot 2}}$

Cancel the common factor.

$e = \frac{5}{2} - \frac{\frac{1}{4}}{\frac{4 \cdot - 1}{4 \cdot 2}}$

Rewrite the expression.

$e = \frac{5}{2} - \frac{\frac{1}{4}}{\frac{- 1}{2}}$

Move the negative in front of the fraction.

$e = \frac{5}{2} - \frac{\frac{1}{4}}{- \frac{1}{2}}$

Multiply the numerator by the reciprocal of the denominator.

$e = \frac{5}{2} - (\frac{1}{4} (- 1 \cdot 2))$

Cancel the common factor of $2$ .

Factor $2$ out of $4$ .

$e = \frac{5}{2} - (\frac{1}{2 (2)} (- 1 \cdot 2))$

Factor $2$ out of $- 1 \cdot 2$ .

$e = \frac{5}{2} - (\frac{1}{2 (2)} (2 \cdot - 1))$

Cancel the common factor.

$e = \frac{5}{2} - (\frac{1}{2 \cdot 2} (2 \cdot - 1))$

Rewrite the expression.

$e = \frac{5}{2} - (\frac{1}{2} \cdot - 1)$

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

$e = \frac{5}{2} - \frac{- 1}{2}$

Move the negative in front of the fraction.

$e = \frac{5}{2} - - \frac{1}{2}$

Multiply $- - \frac{1}{2}$ .

Multiply $- 1$ by $- 1$ .

$e = \frac{5}{2} + 1 (\frac{1}{2})$

Multiply $\frac{1}{2}$ by $1$ .

$e = \frac{5}{2} + \frac{1}{2}$

Combine the numerators over the common denominator.

$e = \frac{5 + 1}{2}$

Add $5$ and $1$ .

$e = \frac{6}{2}$

Divide $6$ by $2$ .

$e = 3$

Substitute the values of $a$ , $d$ , and $e$ into the vertex form $- \frac{1}{8} {(y + 2)}^{2} + 3$ .

$- \frac{1}{8} {(y + 2)}^{2} + 3$

Set $x$ equal to the new right side.

$x = - \frac{1}{8} \cdot {(y + 2)}^{2} + 3$

Step 2

Use the vertex form, $x = a {(y - k)}^{2} + h$ , to determine the values of $a$ , $h$ , and $k$ .

$a = - \frac{1}{8}$

$h = 3$

$k = - 2$

Step 3

Since the value of $a$ is negative, the parabola opens left.

Opens Left

Step 4

Find the vertex $(h, k)$ .

$(3, - 2)$

Step 5

Find $p$ , the distance from the vertex to the focus.

Find the distance from the vertex to a focus of the parabola by using the following formula.

$\frac{1}{4 a}$

Substitute the value of $a$ into the formula.

$\frac{1}{4 \cdot (- \frac{1}{8})}$

Simplify.

Cancel the common factor of $1$ and $- 1$ .

Rewrite $1$ as $- 1 (- 1)$ .

$\frac{- 1 (- 1)}{4 \cdot (- \frac{1}{8})}$

Move the negative in front of the fraction.

$- \frac{1}{4 (\frac{1}{8})}$

Combine $4$ and $\frac{1}{8}$ .

$- \frac{1}{\frac{4}{8}}$

Cancel the common factor of $4$ and $8$ .

Factor $4$ out of $4$ .

$- \frac{1}{\frac{4 (1)}{8}}$

Cancel the common factors.

Factor $4$ out of $8$ .

$- \frac{1}{\frac{4 \cdot 1}{4 \cdot 2}}$

Cancel the common factor.

$- \frac{1}{\frac{4 \cdot 1}{4 \cdot 2}}$

Rewrite the expression.

$- \frac{1}{\frac{1}{2}}$

Multiply the numerator by the reciprocal of the denominator.

$- (1 \cdot 2)$

Multiply $- (1 \cdot 2)$ .

Multiply $2$ by $1$ .

$- 1 \cdot 2$

Multiply $- 1$ by $2$ .

$- 2$

Step 6

Find the focus.

The focus of a parabola can be found by adding $p$ to the x-coordinate $h$ if the parabola opens left or right.

$(h + p, k)$

Substitute the known values of $h$ , $p$ , and $k$ into the formula and simplify.

$(1, - 2)$

Step 7

Find the axis of symmetry by finding the line that passes through the vertex and the focus.

$y = - 2$

Step 8

Find the Axis of Symmetry -8x+24=y^2+4y+4

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