# Help simplifying basic expression with e

• Sep 17th 2011, 08:01 AM
benny92000
Help simplifying basic expression with e
I have x/4 = lny This simplifies to y=e^(x-4)

Can someone help me understand the basic inverse properties of ln and e that would make x/(4 x ln)=y simplify to the answer above? Thanks.
• Sep 17th 2011, 08:16 AM
Siron
Re: Help simplifying basic expression with e
Use the definition of the logarithm: $\ln(x)=y \Leftrightarrow e^{y}=x$
• Sep 17th 2011, 08:18 AM
TKHunny
Re: Help simplifying basic expression with e
I'm not sure "simplify" is the right word.

You should have this property...The following Two statements are identical.

1) $log_{b}(a) = c$
2) $b^{c} = a$

For suitable a, b, and c.

How does this apply to your problem statement?

Revise: See, SIRON even called it a "Definition". It's not really a "simplify" thing.
• Sep 17th 2011, 08:29 AM
benny92000
Re: Help simplifying basic expression with e
I understand the two statements and the conversion you guys give, but I don't know how to apply them correctly to this problem.
• Sep 17th 2011, 11:27 AM
Siron
Re: Help simplifying basic expression with e
You can say: $\frac{x}{4}=\ln(y) \Leftrightarrow e^{\frac{x}{4}}=y$
• Sep 17th 2011, 11:59 AM
e^(i*pi)
Re: Help simplifying basic expression with e
Quote:

Originally Posted by benny92000
Can someone help me understand the basic inverse properties of ln and e that would make x/(4 x ln)=y simplify to the answer above? Thanks.

The natural log needs an argument and this has none. What is the question in full?
• Sep 17th 2011, 12:44 PM
benny92000
Re: Help simplifying basic expression with e
I don't remember the exact question. I understand it now. Thanks!