Question

Let f(x) = 2x^2and g(x) =x-1. Find (f • g)(x), then evaluate when x = 3.

Answer 1

(f • g)(x) = 2(x-1)^2 and (f • g)(3) = 8.

Explanation:

We have, to substitute g(x) into f(x) wherever we see x in f(x),to find (f • g)(x).

Which will give,

(f • g)(x) = f(g(x))

= f(x-1)

= 2(x-1)^2

We have to put x = 3 to evaluate this expression,

(f • g)(3) = 2(3-1)^2

= 2(2)^2

= 8

Therefore,

(f • g)(x) = 2(x-1)^2 and (f • g)(3) = 8.

Answer 2

(f • g)(x) = f(g(x))

= f(x-1)

= 2(x-1)^2

Therefore, (f • g)(3) = 2(2)^2 = 8