Question

If $f\left(x\right)=5x+3$ and $g\left(x\right)=x^2-1$, then $f\left(g\right(2\left)\right)=$

• A. $3$
• B. $13$
• C. $18$
• D. $39$
• E. $168$

Answer 1

The correct option is C $18$

Given, $f\left(x\right)=5x+3$ and $g\left(x\right)=x^2-1$

$\Rightarrow f\left(g\right(2\left)\right)=f(2^2-1)$

$\Rightarrow f\left(g\right(2\left)\right)=f\left(3\right)$

$\Rightarrow f\left(g\right(2\left)\right)=5\times 3+3$

$\Rightarrow f\left(g\right(2\left)\right)=15+3=18$