Question

What is the function written in vertex form?

O f(x) = 5(x + 4) - 80
O fx) = 5(x + 8) - 80
O f(x)=5(x + 4)80
O f(X) = 5(x+ 8)²80

Answer 1

Explanation:

f(x) = 5x^2 + 40x Take out the common factor of 5

f(x) = 5(x^2 + 8x ) Put 1/2 8 squared inside the brackets.

f(x) = 5(x^2 + 8x + 16) x^2 + 8x + 16 is a perfect square

f(x) = 5(x + 4)^2

Here's the tricky part. What you have actually added inside the brackets is 5 * 16 which is equal to 80. You must then subtract 80 outside the brackets.

f(x) = 5(x + 4)^2 - 80. The closest answer appears to be C or maybe A which ever one is closest to my answer.