F(x) =3x; g(x) = 4x^2 +1 which expression is equal to (fog) (x)? a 4x^2 + 3x -1 b 12x^3 + 3x c 36^2 + 1 d 12x^2 + 3 will mark brainliest

d 12x^3 + 3

Step-by-step explanation:

This is a composite function. Just insert g(x) into the x of f(x)

f(x) = 3x

3(4x^2 + 1)

Distribute the three

3(4x^2 + 1)

12x^3 + 3

what’s the question?