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

Apr 5, 2018

Vertex is $\left(\frac{5}{2} , - \frac{57}{4}\right)$

#### Explanation:

$y = {x}^{2} - 5 x - 8$

Vertex is given by $x = - \frac{b}{2 a}$ where a,b refers to $a {x}^{2} + b x + c = 0$

Therefore, $x = - \frac{b}{2 a} = \frac{5}{2 \times 1} = \frac{5}{2}$

Sub $x = \frac{5}{2}$ into $y = {x}^{2} - 5 x - 8$ to get the y-value

$y = - \frac{57}{4}$

Vertex is $\left(\frac{5}{2} , - \frac{57}{4}\right)$