Diketahui (f o g)(x) = 2x - 3/x + 4; x ≠ -4
dan g(x) = 1 - x, maka f(x) = ....
Jawab:
(f o g)(x) = 2x - 3
x + 4
f[g(x)] = 2x - 3
x + 4
f(1 - x) = 2x - 3
x + 4
Misal:
1 - x = a ➙ x = 1 - a
f(a) = 2(1 - a) - 3
1 - a + 4
= 2 - 2a - 3
5 - a
= -1 - 2a
5 - a
= 2a + 1
a - 5
Jadi f(x) = 2x + 1
x - 5