# What is the axis of symmetry for the graph y= -x^2-8x+10?

Aug 2, 2017

$x = - 4$

#### Explanation:

$\text{the axis of symmetry passes through the vertex and has }$
$\text{equation}$

•color(white)(x)x=c

$\text{where c is the value of the x-coordinate of the vertex}$

$\text{for a parabola in standard form } a {x}^{2} + b x + c$

${x}_{\textcolor{red}{\text{vertex}}} = - \frac{b}{2 a}$

$y = - {x}^{2} - 8 x + 10 \text{ is in standard form}$

$\text{with } a = - 1 , b = - 8 , c = 10$

$\Rightarrow {x}_{\textcolor{red}{\text{vertex}}} = - \frac{- 8}{- 2} = - 4$

$\Rightarrow \text{axis of symmetry is } x = - 4$
graph{(y+x^2+8x-10)(y-1000x-4000)=0 [-80, 80, -40, 40]}