Question

Consider the functions
f(x) = 3x2 and g(x) = 2(x + 9).
Find f[g(−7)].

Please show the work? Thanks.

Answer 1

Find g(-7) by plugging -7 in for g(x)

Answer 2

\[g(-7)=2((-7)+9)\]

Answer 3

\[g(-7)=4\]

Answer 4

Then, plug 4 into f(x).

Answer 5

\[f(4)=3(4)^{2}\]

Answer 6

\[f(4)=48\]

Answer 7

Plug in g(-7) into g(x) and then plug in that solution to f(x):\[g(-7)=2(-7+9)\]\[g(-7)=2(2)\]\[g(-7)=4\]now plug in \(4\) to \[f(x)=3(4)^2\]\[f(x)=3(16)\]\[f(x)=48\]
and thus: \(\largef[g(-7)]=48\)

Answer 8

Oh, thank you! I hate complicated functions like these. Thanks to both of you!

Answer 9

No Problem :)

Answer 10

Np..