Math help with problem

Question

Given that f(x)=4x−1 and g(x)=9x+4, determine each of the following. Make sure to fully simplify your answer.

(a) (f∘g)(x)=   

(b) (g∘f)(x)=  

(c) (f∘f)(x)=   

(d) (g∘g)(x)=

Answer 1

f(x)=4x-1

g(x) = 9x+4

a) f(g(x)) = 4(9x+4)+1 = 36x+17

b) g(f(x)) = 9(4x-1)+4 =36x-5

c) f(f(x)) =4(4x-1) -1 = 16x -5

d) g(g(x)) = 9(9x+4)+4 = 81x+40