solve the functions

Question

Find (f ○ g)(x) and (g ○ f)(x) for the pair of functions.
f(x) = x2 + 2x, g(x) = 9x + 1

(f ○ g)(x) =

 

 

(g ○ f)(x) =

Answer 1

f(x) = x² + 2x, g(x) = 9x + 1

(f ○ g)(x) = f[g(x)] = [9x+1]² +2[9x+1]   ... do you see how the x terms of f are replaced by g(x) in each case?

 

Now just simplify.

 

For the (g ○ f)(x) =, just do 9[ ] + 1 where you substitute f(x) into the empty [ ]