Question

Which of the following functions is quadratic?

f(x)=5^2

f(x)=3(x-4)(x+3)

f(x)=2/3

f(x)=2x^3+3x^2-5

Answer 1

f(x)=3(x-4)(x+3)

Explanation:

Quadratic function follows the f(x) = ax^2 +bx+c pattern

f(x)=3(x-4)(x+3) after multiplying out is equal to

f(x)=(3x-12)(x+3) = (3x^2+9x-12x-36) = (3x^2-3x-36)

f(x) = (3x^2-3x-36)

where

a = 3

b = -3

c = -36