Answer
$f(g(x))=25x^2+1$
$g(f(x))=5x^2+5$
Work Step by Step
f of g(x) means $f(g(x))$
$g(x)$ is given as $5x$
So $f(g(x))=f(5x)=(5x)^2+1$
Therefore $f(g(x))=25x^2+1$
g of f(x) means $g(f(x))$
$f(x)$ is given as $x^2+1$
So $g(f(x))=g(x^2+1)=5(x^2+1)$
Therefore $g(f(x))=5x^2+5$
