Find f(g(x)) f(x)=3x g(x)=3x

$f (x) = 3 x$ $g (x) = 3 x$

Set up the composite result function.

$f (g (x))$

Evaluate $f (3 x)$ by substituting in the value of $g$ into $f$ .

$f (3 x) = 3 (3 x)$

Multiply $3$ by $3$ .

$f (3 x) = 9 x$