The first three steps in writing f(x) = 40x + 5x2 in vertex form are shown. Write the function in standard form. f(x) = 5x2 + 40x
Factor a out of the first two terms. f(x) = 5(x2 + 8x)
Form a perfect square trinomial.(eight-halves) squared = 16
f(x) = 5(x2 + 8x + 16) – 5(16)
What is the function written in vertex form?

f(x) = 5(x + 4) – 80
f(x) = 5(x + 8) – 80
f(x) = 5(x + 4)2 – 80
f(x) = 5(x + 8)2 – 80