Math

QuestionEvaluate the following using f(x)=7x1f(x)=7x-1 and g(x)=xg(x)=|x|: (a) (fg)(5)(f \circ g)(-5) (b) (gf)(3)(g \circ f)(3) Find (fg)(5)=(f \circ g)(-5)= (Simplify your answer.)

Studdy Solution

STEP 1

Assumptions1. We have two functions, f(x)=7x1f(x)=7x-1 and g(x)=xg(x)=|x|. . We need to evaluate the compositions of these functions, namely (fg)(5)(f \circ g)(-5) and (gf)(3)(g \circ f)(3).

STEP 2

The composition of two functions, (fg)(x)(f \circ g)(x), is defined as f(g(x))f(g(x)). This means that we first apply the function gg to xx, and then apply the function ff to the result.

STEP 3

To evaluate (fg)(5)(f \circ g)(-5), we first apply the function gg to 5-5.g(5)=5g(-5) = |-5|

STEP 4

Calculate the absolute value of -.
g()==g(-) = |-| =

STEP 5

Now, we apply the function ff to the result from step4.
f(g(5))=f(5)=751f(g(-5)) = f(5) =7 \cdot5 -1

STEP 6

Calculate the value of 51 \cdot5 -1.
f(g(5))=51=34f(g(-5)) = \cdot5 -1 =34So, (fg)(5)=34(f \circ g)(-5) =34.

STEP 7

Now, let's evaluate (gf)(3)(g \circ f)(3). This means we first apply the function ff to 33.
f(3)=731f(3) =7 \cdot3 -1

STEP 8

Calculate the value of 7317 \cdot3 -1.
f(3)=731=20f(3) =7 \cdot3 -1 =20

STEP 9

Now, we apply the function gg to the result from step8.
g(f(3))=g(20)=20g(f(3)) = g(20) = |20|

STEP 10

Calculate the absolute value of 2020.
g(f(3))=20=20g(f(3)) = |20| =20So, (gf)(3)=20(g \circ f)(3) =20.

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