Question

Jika f(x) =3^x-1 , hitung nilai f^-1(81) .

Answer 1

Verified answer

F(x) = y = 3^(x - 1)
y = 3^x /3
3y = 3^x
log (3y) = x log 3
x = ³log (3y)

f^-1 (x) = ³log (3x)
f^-1 (81) = ³log (3 . 81)
f^-1 (81) = ³log 3^5
f^-1 (81) = 5