Select the correct answer.

Consider these functions:
[tex]$
\begin{array}{l}
f(x)=5x^2 + 2 \\
g(x)=x^2 - 1
\end{array}
$[/tex]

What is the value of [tex][tex]$g(f(-1))$[/tex][/tex]?

A. 2
B. 8
C. 22
D. 48



Answer :

To determine the value of [tex]\( g(f(-1)) \)[/tex], let’s follow these steps:

1. First, evaluate [tex]\( f(-1) \)[/tex]:
[tex]\[ f(x) = 5x^2 + 2 \][/tex]
Substitute [tex]\( x = -1 \)[/tex] into the function [tex]\( f(x) \)[/tex]:
[tex]\[ f(-1) = 5(-1)^2 + 2 \][/tex]
Simplify the equation:
[tex]\[ (-1)^2 = 1 \][/tex]
Therefore,
[tex]\[ f(-1) = 5 \cdot 1 + 2 = 5 + 2 = 7 \][/tex]

2. Next, evaluate [tex]\( g(f(-1)) \)[/tex] which is [tex]\( g(7) \)[/tex]:
[tex]\[ g(x) = x^2 - 1 \][/tex]
Substitute [tex]\( x = 7 \)[/tex] into the function [tex]\( g(x) \)[/tex]:
[tex]\[ g(7) = 7^2 - 1 \][/tex]
Simplify the equation:
[tex]\[ 7^2 = 49 \][/tex]
Therefore,
[tex]\[ g(7) = 49 - 1 = 48 \][/tex]

So, the value of [tex]\( g(f(-1)) \)[/tex] is [tex]\( \boxed{48} \)[/tex]. The correct answer is [tex]\( \text{D. 48} \)[/tex].