Question 42762
This is a composite function which means one polynomial is inserted into another polynomial.
First take g(x)=x^2+7.
Substitute f(x) wherever there is an x in g(x).
g of f = (5x+7)^2 + 7
= (5x+7)(5x+7) + 7
= 25x^2 + 70x + 56