Find the Axis of Symmetry (y+2)^2=-4x

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

Step 1

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

Rewrite the equation as $- 4 x = {(y + 2)}^{2}$ .

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

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

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

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

Simplify the left side.

Cancel the common factor of $- 4$ .

Cancel the common factor.

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

Divide $x$ by $1$ .

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

Simplify the right side.

Move the negative in front of the fraction.

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

Reorder terms.

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

Step 2

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

$a = - \frac{1}{4}$

$h = 0$

$k = - 2$

Step 3

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

Opens Left

Step 4

Find the vertex $(h, k)$ .

$(0, - 2)$

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.

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

Simplify.

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

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

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

Move the negative in front of the fraction.

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

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

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

Divide $4$ by $4$ .

$- \frac{1}{1}$

Cancel the common factor of $1$ .

Cancel the common factor.

$- \frac{1}{1}$

Rewrite the expression.

$- 1 \cdot 1$

Multiply $- 1$ by $1$ .

$- 1$

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 (y+2)^2=-4x

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