I'm not finding correctly the derivative of:

I do the following:

lim h-> 0:

Then, of course, when I substitute "0" for "h", I get an answer of 0.

The correct answer is:

Where did I go wrong?

Thank you!

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- March 21st 2011, 01:33 PMJennyFlowersFinding a derivative.
I'm not finding correctly the derivative of:

I do the following:

lim h-> 0:

Then, of course, when I substitute "0" for "h", I get an answer of 0.

The correct answer is:

Where did I go wrong?

Thank you! - March 21st 2011, 01:50 PMpickslides
In the second line of your workings...

- March 21st 2011, 02:08 PMJennyFlowers
Is there a simpler way to solve this while still using the definition of the derivative? I'm sure I did this before without expanding it the way you have, I just don't remember how.

Thanks again. :) - March 21st 2011, 02:22 PMJennyFlowers
Ah, found it. I used the alternate definition of the derivative to do it.

Works out to:

Which solves my problem as well as the derivative from the standard definition.

Thanks for the help! - March 21st 2011, 02:33 PMpickslides
- March 21st 2011, 02:37 PMJennyFlowers
Right, but I wasn't allowed to find this derivative using the power rule. I was required to find it using either the definition or the alternate definition!