Can someone help me to derivatex^x^x? I'm starting to belive it's not possible... : D heeelp! :) Thank you in advance!

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- Jan 24th 2007, 05:20 AMkukkeballTricky derivation...
Can someone help me to derivate

**x^x^x**? I'm starting to belive it's not possible... : D heeelp! :) Thank you in advance! - Jan 24th 2007, 05:42 AMearboth
- Jan 24th 2007, 05:49 AMAfterShock
Oh, it's perfectly possible, and fun too ;) .

I have class soon, but I will get you started.

First, what is the derivative of x^x?

We have y = x^x

Note: x > 0

ln(y) = ln(x^x)

ln(y) = x*(ln(x))

Differentiate both sides with respect to x;

y'(1/y) = ln(x) + x*(1/x) = (ln(x) + 1)

y' = (ln(x) + 1)*y

But recall y = x^x

y' = (ln(x) + 1)*x^x

Now you can use this to find the derivative of x^x^x. - Jan 24th 2007, 06:13 AMAfterShock
- Jan 24th 2007, 10:48 AMearboth
- Jan 25th 2007, 08:54 AMkukkeball
So what's the correct answer... i got something crazy... : F

- Jan 25th 2007, 11:34 AMSoroban
Hello, kukkeball!

Here's another approach . . .

Quote:

Differentiate: .

Take logs: .

Take logs again: .

Differentiate implicitly (**very**carefully) . . .

. .

We have: .

Then: .

Therefore: .