I really need help with these three questions!

Question

Let f(x) = x^3 - 1 and g(x) = 3x. What is (g ? f)(-2), or g(f(-2))?

 
 

Let f(x) = 3x and g(x) = x^2 + 2. What is (g ? f)(-3), or g(f(-3))?


 

Let f(x) = x^2 - 1 and g(x) = 2x. What is (g ? f)(4), or g(f(4))?

Answer 1

g(f(-2)) top problem

g of f of -2.  This is a composite function where you want to work from the inner parens out.  So start with the f(-2)

first plug in -2 for x in f(x)

f(-2)=(-2)^3-1 = -8-1 = -9

 

now plug this value in for the input  in the  g function

g(-9)=3(-9) = -27

 

Now you should be able to solve the other two, as you just use the same approach