Answer
$(f\circ{g})'(0)=6$
Work Step by Step
$(f\circ{g})(x)=f(g(x))$
$\frac{d}{dx}(f(g(x))=f'(g(x))\times{g'(x)}$
$(f\circ{g})'(0)=f'(g(0))\times{g'(0)}$
$(f\circ{g})'(0)=f'(0)\times{3}$
$(f\circ{g})'(0)=2\times{3}$
$(f\circ{g})'(0)=6$