Question 698148
To get f of g  : 
take the info for g(x) (in this case 2x+2) and plug that into the equation for f(x).
So every place you see an 'x' in the f(x) equation, plug in '2x+2' (which is g(x)

{{{f(g(x)) = 3(g(x))^2 + 1}}}

{{{f(g(x)) = 3(2x+2)^2 + 1}}}

{{{f(g(x)) = 3(4x^2 + 8x + 4) + 1}}}

{{{f(g(x)) = 12x^2 + 24x + 12 + 1}}}
{{{f(g(x)) = 12x^2 + 24x + 13}}}