How do I find the vertex of f(x) = x^2 + 4x - 16?

Answer 1

You find -b/2a

This is your x-value for your vertex

Plug the x-value into your function for x to find what the y is

Then represent the vertex as a point (x,y)

Answer 2

You could in this simple case represent it in the "vertex" form - by using "completing the square:

(x+2)^2 - 4 - 16

(x+2)^2 - 20

The vertex coordinates are (-2, -20)

Answer 3

f(x) = ax² + bx + c

To find the vertex...

x = -b/2a = -4/2(1) = -4/2 = -2

f(-2) = (-2)² + 4(-2) - 16 = 4 - 8 - 16 = -20

Your vertex is (-2,-20).