Jika f(x)= x-8, g(x)=2x2+3 dan f o g(x)=25, maka tentukan nilai x?

f(x) = x - 8
g(x) = 2x² + 3

(fog) (x) = 25
f(2x² + 3) = 25
(2x² + 3) - 8 = 25
2x² - 5 = 25
2x² = 25 + 5
2x² = 30
x² = 30/2
x² = 15
x = ± √15

Maka x = √15 atau x = - √15