What is the vertex form of  y = -x^2 + 8x − 13?

Mar 29, 2018

$y = - {\left(x - 4\right)}^{2} + 3$

Explanation:

$y = - {x}^{2} + 8 x - 13$
x-coordinate of vertex:
$x = - \frac{b}{2 a} = - \frac{8}{-} 2 = 4$
y-coordinate of vertex:
$y \left(4\right) = - 16 + 32 - 13 = 3$
Vertex form:
$y = - {\left(x - 4\right)}^{2} + 3$