218k views
3 votes
f(x) = 3x - 7 and g(x) = -2x -6Find (f o g)(4) (see image)I need to understand the step by step steps for how to solve this problem

f(x) = 3x - 7 and g(x) = -2x -6Find (f o g)(4) (see image)I need to understand the-example-1
User Allmhuran
by
3.8k points

1 Answer

6 votes

\begin{gathered} f(x)=3x-7 \\ g(x)=-2x-6 \end{gathered}

Composition of functions:


(f\circ g)(x)=f(g(x))

1. Find (fog)(x): Substitute the imputs (x-values) in f for function g:


(f\circ g)(x)=3(-2x-6)-7

2. Simplify:


\begin{gathered} (f\circ g)(x)=-6x-18-7 \\ (f\circ g)(x)=-6x-25 \end{gathered}

3. Find (fog)(4). Evaluate the fucntion (fog) when x=4:


\begin{gathered} (f\circ g)(4)=-6(4)-25 \\ (f\circ g)(4)=-24-25 \\ (f\circ g)(4)=-49 \end{gathered}Then, (fog)(4) is:
(f\circ g)(4)=-49

User Ronen Yacobi
by
3.5k points