tentukan invers fungsi dari f (x) = 2x / x +1

Materi : Fungsi Invers dan Komposisi
Kelas : X SMA - XI SMA

f(x) = 2x / (x + 1)
y = 2x / (x + 1)
y(x + 1) = 2x
yx + y = 2x
yx - 2x = -y
x(y - 2) = -y
x = -y / (y - 2)

f^-1 (x) = -x / (x - 2) sampai sini , sudah bisa
f^-1 (x) = -1 + x/2

f (x) = 2x / x +1
y = 2x / x +1
y(x + 1) = 2x
xy + y - 2x = 0
xy - 2x = -y
x (y - 2) = -y
x = -y / (y - 2)
jadi 
f⁻¹(x) = -x / (x - 2)