# What is the vertex of  y= x^2 - 4x- 15?

Jan 2, 2016

(2 , -19 )

#### Explanation:

this is a quadratic function of the form $a {x}^{2} + b x + c$

here a = 1 and b = -4
the x-coordinate of the vertex can be found using x = - b/2a

x = -( -4/2 )= 2
and y = ${2}^{2} - 4 \times 2 - 15$
y = 4 - 8 -15
y = -19