Question

Given the function f(x) = 3^(x), find the value of f^(-1)(81).

Answer 1

We need the inverse again. Remember how?

Answer 2

y = 3^x
x = 3^y
Solve for y from here.

Answer 3

What are your answer choices I am getting something weird

Answer 4

f^(-1)(81) = 1
f^(-1)(81) = 2
f^(-1)(81) = 3
f^(-1)(81) = 4

Answer 5

so would it just be C?

Answer 6

I get
inverse = \[\frac{ \ln (x) }{ \ln (3) }\]

Answer 7

\[\frac{ \ln (81) }{ \ln (3) }\]

Answer 8

i'm kind of confused as to how you got that

Answer 9

hold on one second

Answer 10

okie dokie

Answer 11

to be honest, I just checked it on an inverse calculator and that's what i got, so

Answer 12

I think the answer will be 4. I put in ln81 and got 4.39444915467
and ln3 and got 1.09861228867
Divide them:
4.39444915467/1.09861228867 = 3.999999
So 4

Answer 13

Hope that is ok...

Answer 14

ah okay i see what you did now

Answer 15

ok cool