What is the vertex of the graph of y = x2 + 4x?
(–2, –12)
(–2, –8)
(–2, –6)
(–2, –4)

The vertex of the parabola (quadratic function) is (-2,-4)

Fourth option: (-2,-4)

Solution:

y=x^2+4x

y=ax^2+bx+c; a=1, b=4, c=0

Vertex: V=(h,k)

h=-b/(2a)

h=-4/(2(1))

h=-4/2

h=-2

y=x^2+4x

k=y=h^2+4h

k=(-2)^2+4(-2)

k=4-8

k=-4

Vertex: V=(h,k)

Vertex: V=( -2, -4)