## anonymous one year ago Given the function f(x) = 3^(x), find the value of f^(-1)(81).

1. anonymous

We need the inverse again. Remember how?

2. anonymous

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

3. anonymous

4. anonymous

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

5. anonymous

so would it just be C?

6. anonymous

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

7. anonymous

$\frac{ \ln (81) }{ \ln (3) }$

8. anonymous

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

9. anonymous

hold on one second

10. anonymous

okie dokie

11. anonymous

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

12. anonymous

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

13. anonymous

Hope that is ok...

14. anonymous

ah okay i see what you did now

15. anonymous

ok cool