# Ln problem

• March 5th 2008, 11:46 AM
farso
Ln problem
Hi

Im halfway though a homework problem and i was hoping for a little insight into how one would go about solving the problem.

Thanks for whatever you can offer!

The question:

$\ln(y+\sqrt{2y-1})+\ln(y-\sqrt{2y-1})=0$

So far ive got them all to the same side, added the logs and brought it down to $\ln(y^2-2y-1)=0$ and was wondering how to remove the ln in order to solve the equation?

Thank you very much
• March 5th 2008, 11:52 AM
Krizalid
It's actually $\ln(y^2-2y+1)=0,$ and this is pretty familiar.
• March 5th 2008, 11:57 AM
farso
So why not give us a clue? ;)
• March 5th 2008, 01:03 PM
Peritus
here's a big clue:

if:

$\ln \left( {y^2 - 2y + 1} \right) = 0
$

then:

$y^2 - 2y + 1 = 1
$

can you continue?
• March 5th 2008, 02:08 PM
farso
Yeah, i think so; thanks.

I just had to raise each side as a power of e to get rid of ln right?
• March 5th 2008, 02:33 PM
bobak
Quote:

Originally Posted by farso
Yeah, i think so; thanks.

I just had to raise each side as a power of e to get rid of ln right?

yeah, that step is commonly refereed to as "anti-logging"