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4 votes
Given the definitions of f(x) and g(x)

below, find the value of f(g(-4)). F(x)=4x+6 g(x)=x^ 2+x-9

User Thepoosh
by
6.9k points

1 Answer

5 votes

Answer:


f(g(-4)) = 18

Explanation:

Given


f(x) = 4x + 6


g(x) = x^2 + x - 9

Required

Find f(g(-4))

First, calculate f(g(x))

We have:


f(x) = 4x + 6


f(g(x)) = 4g(x) + 6

Substitute:
g(x) = x^2 + x - 9


f(g(x)) = 4[x^2 + x - 9] + 6

Open bracket


f(g(x)) = 4x^2 + 4x - 36 + 6


f(g(x)) = 4x^2 + 4x-30

Substitute
-4 for
x


f(g(-4)) = 4*(-4)^2 + 4*(-4)-30


f(g(-4)) = 64 -16 -30


f(g(-4)) = 18

User Shontel
by
6.1k points
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