Question

What is the vertex of the graph of y = x2 + 4X?

O (-2, -12)
O (-2,-8)
O(-2,-6)
O (-2,-4)

Answer 1

vertex = (- 2, - 4 )

Explanation:

Given a parabola in standard form

y = ax² + bx + c ( a ≠ 0 )

Then the x- coordinate of the vertex is

x = -
`(b)/(2a)`

y = x² + 4x ← is in standard form

with a = 1, b = 4, c = 0 , then

x = -
`(4)/(2)` = - 2

Substitute x = - 2 into the equation for corresponding value of y

y = (- 2)² + 4(- 2) = 4 - 8 = - 4

vertex = (- 2, - 4 )