Question

Which of the following forms of f(x)
reveals its maximum value without having to be rewritten?(1 point)
Responses

f(x)=−2x2+4x+16

f of x is equal to negative 2 x squared plus 4 x plus 16

f(x)=−2(x−1)2+18

f of x is equal to negative 2 times open paren x minus 1 close paren squared plus 18

f(x)=−2(x2−2x−8)

f of x is equal to negative 2 times open paren x squared minus 2 x minus 8 close paren

f(x)=−2(x−4)(x+2)

Answer 1

f(x) = −2(x−1)^2 + 18.

This is the vertex form a(x−h)^2 + k with a = −2 < 0, so the parabola opens downward and the maximum value is k = 18, occurring at x = 1.