# Math Help - Inverse of function

1. ## Inverse of function

How do I find the inverse of this function?

y = ln(x + 8)

2. ## Re: Inverse of function

Originally Posted by Oldspice1212
How do I find the inverse of this function?

y = ln(x + 8)
Exchange the x and y to get

$x=\ln(y+8)$

and now solve for y. This will be the inverse function.

3. ## Re: Inverse of function

So x would = e^y+e^8?

4. ## Re: Inverse of function

Originally Posted by Oldspice1212
So x would = e^y+e^8?
Not quite. You are correct that the inverse of the natural log is the exponential base e, but be careful the first step should be

$e^x=e^{\ln(y+8)}$

Can you finish from here?

5. ## Re: Inverse of function

Oh right! Thanks, I'll get back to you with my answer :P

6. ## Re: Inverse of function

Uh I got y = e^x-8

7. ## Re: Inverse of function

That is correct.

8. ## Re: Inverse of function

Sweet! Thanks for the hint, I can't believe I forgot that!