tolong bantu saya perlu sekarang

f(x) = 3^(x-1)
y = 3^(x-1)
x - 1 = ³log y
x = (³log y) + 1
f-¹(x) = (³log x) + 1
f-¹(81) = (³log 81) + 1
f-¹(81) = (4) + 1
f-¹(81) = 5