PROBLEM
Check if f(x)=5x+9 and g(x)=5x−9 are inverse functions by finding (f∘g)(x) and (g∘f)(x).
STEP 1
Assumptions1. The function f(x)=5x+9
. The function g(x)=5x−9
3. We need to determine if f(x) and g(x) are inverse functions. This can be done by checking if (f∘g)(x)=x and (g∘f)(x)=x.
STEP 2
First, we will find the composition of f and g, denoted as (f∘g)(x), which means we substitute g(x) into f(x).
(f∘g)(x)=f(g(x))
STEP 3
Substitute g(x) into f(x).
(f∘g)(x)=f(5x−9)
STEP 4
Replace x in f(x) with x−9.
(f∘g)(x)=(x−9)+9
STEP 5
implify the expression.
(f∘g)(x)=x−9+9
STEP 6
Further simplify the expression.
(f∘g)(x)=x
STEP 7
Now, we will find the composition of g and f, denoted as (g∘f)(x), which means we substitute f(x) into g(x).
(g∘f)(x)=g(f(x))
STEP 8
Substitute f(x) into g(x).
(g∘f)(x)=g(5x+)
STEP 9
Replace x in g(x) with 5x+9.
(g∘f)(x)=55x+9−9
STEP 10
implify the expression.
(g∘f)(x)=55x
STEP 11
Further simplify the expression.
(g∘f)(x)=x
SOLUTION
Since both (f∘g)(x)=x and (g∘f)(x)=x, we can conclude that f(x) and g(x) are inverse functions.
Thus, g(x) is the inverse function of f(x).
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