g(x) = 2x + 3
f(x) = x^2 + 7
g(f(x)) = 2(x^2 + 7) + 3
g(f(x)) = 2x^2 + 14 + 3
g(f(x)) = 2x^2 + 17
when g(f(x)) = 25 then
2x^2 + 17 = 25
2x^2 - 8 = 0
2(x^2 - 4) = 0
2(x+2)(x-2) = 0
x + 2 = 0; x = -2
x - 2 = 0; x = 2
Answer
x = 2 or - 2
