Question

what are the vertext and x-intercept of the graph of y=(x+4)(x-2)? select one answer for the vertext and one for the x-intercepts

Answer 1

x-intercepts (-4, 0) and (2,0)

Vertex is ( - 1, -9)

Explanation:

X- intercepts

y=0

(x+4)(x-2)=0

x = - 4, x =2 or at can be written as (-4, 0) and (2,0)

Vertex

y = (x+4)(x - 2) =x² -2x +4x - 8 = x² + 2x - 8²

y = x² + 2x - 8

To find vertex we need to write equation in vertex form by completing square.

y = x²+2x -8 = x² + 2*1*x + 1² - 1² - 8 = (x+1)² - 9

y = (x+1)² - 9

Vertex is ( - 1, -9).