Question

What is the vertex of the quadratic function y = (x + 2)(x -8)?

Answer 1

(3, -25)

Explanation:

Given

• y = (x + 2)(x -8) in factored form

Writing is standard form

• y = x² - 8x + 2x - 16 =
• = x² - 6x - 16

Vertex is obtained at x = -b/2a

• x = -(-6)/2*1 = 3

y- coordinate is:

• y = 3² - 6*3 - 16 = 9 - 18 - 16 = -25

So vertex is:

• (3, -25)