Mohon bantuannya pakai cara untuk soal matematika berikut ini. Terima kasih.

f(x) = y
f-¹(y) = x
jadi f(x+1 / 2x-1) = 2/x
f-¹(2/x) = (x+1) / (2x-1)
f-¹(-4) = ...
maka
2/x = -4
2 = -4x
x = 2/-4 = -1/2
f-¹(-1/2) = (-½+1) / (2(-½)-1)
= (-½+2/2) / (-1-1)
= (1/2) / -2
= -1/4