In order to calculate the composite function h(g(x)), we need to switch x by g(x) in the function h(x).
So we have:
[tex]\begin{gathered} h(x)=3x^2+2x \\ h(g(x))=3g(x)^2+2g(x) \\ h(g(x))=3(9x-2)^2+2(9x-2) \\ h(g(x))=3(81x^2-36x+4)+18x-4 \\ h(g(x))=243x^2-108x+12+18x-4 \\ h(g(x))=243x^2-90x+8 \end{gathered}[/tex]
