Question 837984
Form the composition, and then plug-in {{{x=-2}}}; maybe easier.
{{{g(x)=2x}}}, and {{{h(x)=x^2+4}}}.
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{{{g(h(x))=2(x^2+4)=2x^2+8}}}
Let x=-2.
{{{g(h(-2))=2(-2)^2+8}}}
{{{g(h(-2))=8+8=16}}}
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I did not check your work too carefully, but you showed the same result.