Ln X

**kid funky fried** · March 23rd 2008, 07:02 PM

Does (LN x)^3 = LN^3 x ?

**topsquark** · March 23rd 2008, 07:06 PM

Originally Posted by kid funky fried

Does (LN x)^3 = LN^3 x ?

It depends on the context. $ln^3(x)$ can either mean $ln(x) \cdot ln(x) \cdot ln(x)$ or it can mean $ln(ln(ln(x)))$ , which are two very different things. I typically use it as the former expression, but there are cases where you would want to use it for the latter.

Edit: By the way, note that the function is ln(x), not Ln(x) or LN(x). Mathematics (and Physics, and Engineering, and...) is a "case-sensitive" field of study.

-Dan

**mr fantastic** · March 23rd 2008, 07:07 PM

Originally Posted by kid funky fried

Does (LN x)^3 = LN^3 x ?

It's not notation I'd use, but yes, I suppose it does.

As long as you realise it's NOT LN (x^3)

**kid funky fried** · March 23rd 2008, 07:12 PM

thx.
I will make sure to use the proper case next time.
My answer book was using both expressions so i was beginning to wonder.

**Plato** · March 24th 2008, 03:07 AM

In may be helpful to note that the notation $\left( {\ln \left( x \right)} \right)^n$ is used by almost all computer algebra systems.

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