f(x) = 3x^2 + 2x - 4 f(2) and f(4)
f(x) = 3x^2 + 2x -4
f(2) = 3(2)^2 + 2(2) - 4
f(2) = 3(4) + 4 - 4
F(2) = 12 + 4-4
f(2) = 12
*****
F(4)= 3(4)^2+2(4)-4
f(4) = 3(16) +8-4
f(4) = 48 =-4
f(4) = 51
f(2) = 12 is correct.
There is an arithmetic error in the last step in the calculation of f(4).
f(4) = 3(16) +8-4
f(4) = 48 +4
f(4) = 52