Answer
$(f\circ g)(x)=(x+3)^2$
$(g \circ f)(x) = x^2+3$
Work Step by Step
RECALL:
(1) $(f \circ g)(x) = f[g(x)]$
(2) $(g \circ f)(x) = g[f(x)]$
Thus,
$(f\circ g)(x)= f[(g(x)]$
$\\(f\circ g)(x)=(x+3)^2$ (Substitute $x+3$ to $x$ in $f(x)$)
and
$(g \circ f)(x) = g[f(x)]$
$(g \circ f)(x) = x^2+3$ (Substitute $x^2$ to $x$ in $g(x)$)
