Question

If
f(x) = x2 + 2x - 4
and
g(x) = 3x + 1
Find
f(g(x)) = [? ]x2 + [ ]+х

Answer 1

f(g(x)) = 9x^2 +12x -1

Explanation:

f(g(x)) means you replace the x in f(x) with g(x), which is 3x + 1:

(3x+1)^2 + 2(3x+1) - 4

then expand and simplify:

(3x+1)(3x+1) + 6x+2 - 4

9x^2+6x+1 + 6x+2 - 4

and then collect all like terms:

9x^2

6x + 6x = 12x

1 + 2 - 4 = -1