Question 7848
If {{{f(x) = 3x^2 + 4}}}, then to find f(x+1), substitute the (x+1) everywhere there is an x in the first function.

{{{f(x+1) = 3(x+1)^2 + 4}}}
{{{f(x+1) = 3(x^2 + 2x + 1) + 4}}}
{{{f(x+1) = 3x^2 + 6x + 3 + 4}}}
{{{f(x+1) = 3x^2 + 6x + 7}}}