1. Jika g(x) = x^2 - 3x dan gof (x) = x^4 - 3x^2... maka f(x) ?

(gof) (x) = x⁴ - 3x²
f(x)² - 3f(x) = x⁴-3x²
f(x)² - 3f(x) + 2= x⁴-3x²+2
((f(x) -1)(f(x) -2) = (x²-2)(x²-1)

f(x) - 1 = x²-2
f(x) = x²-2+1
f(x) = x²-1

f(x) -2 = x²-1
f(x) = x²-1+2
f(x) = x²+1

(g o f)(x) = x^4 - 3x^2
g(f(x)) = x^4 - 3x^2
Misal f(x) = a
g(a) = x^4 - 3x^2
a^2 - 3a = x^4 - 3x^2
a^2 - 3a + 9/4 = x^4 - 3x^2 + 9/4
(a - 3/2)^2 = (x^2 - 3/2)^2
a - 3/2 = x^2 - 3/2
a = x^2
f(x) = x^2