Question

What is f(x) = 8x2 + 4x written in vertex form?

f(x) = 8(x + one-quarter) squared – one-half
f(x) = 8(x + one-quarter) squared – one-sixteenth
f(x) = 8(x + one-half) squared – 2
f(x) = 8(x + one-half) squared – 4

Answer 1

f(x) = 8x^2 + 4x = 8(x^2 + 1/2 x)
Complete the square: x^2 + 1/2 x = (x + 1/4)^2 − 1/16
So f(x) = 8(x + 1/4)^2 − 8(1/16) = 8(x + 1/4)^2 − 1/2

Answer: f(x) = 8(x + one-quarter)^2 − one-half.