Question

Given the definitions of f(x) and g(x) below, find the value of (g o f) (-3)

f(x)=2x^2+6x+9
g(x)=3x-6

Answer 1

21

Explanation:

(g o f) (-3) = g ( f(-3) )

First, let's find f(-3):

f(x)=2x²+6x+9

f(-3)=2(-3²)+6(-3)+9

f(-3)=18-18+9

f(-3)=9

Now that we know the value of f(-3), we can sub this into g(f(-3)):

g ( f(-3) ) = g(9)

Find g(9):

g(9)=3x-6

g(9)=3(9)-6

g(9)=27-6

g(9)=21