# What is the vertex of y= -5x^2 + 8x - 13 ?

Jul 9, 2018

$x = \frac{4}{5} , y = - \frac{49}{5}$

#### Explanation:

We get

$y ' \left(x\right) = - 10 x + 8$ (to find the vertex coordinates)
$y ' \left(x\right) = 0$ if $x = \frac{4}{5}$

now we compute the $y$ coordinate:

$f \left(\frac{4}{5}\right) = - 5 \cdot \frac{16}{25} + 8 \cdot \frac{4}{5} - 13 = \frac{32 - 16 - 65}{5} = - \frac{49}{5}$