What are the coordinates of the vertex?

Question

Let f (x) = 2 (x – 3) (x + 5).

What are the coordinates of the vertex?

A. (-1,-32)

B. (1, –24)

C. (2,-14)

D. There is not enough information to find the vertex.

Answer 1

correct answer is A) (-1,-32)

expand 2(x-3)(x+5) to 2(x^2+2x-15)

separate the constant term and complete the square

2(x^2 +2x +1) -2(15)-2

= 2(x+1)^2 -32

that's in the vertex form a(x-h)^2 + k where (h,k) is the vertex

here (h,k) is (-1,-32)