could you please help me to solve this problem please. Thank you.

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- Feb 28th 2009, 09:54 PMthangbelimit problem

could you please help me to solve this problem please. Thank you.

- Mar 1st 2009, 03:36 AMmr fantastic
Several approaches are possible.

There's a simple one if you know differential calculus ..... you can consider the function . Then, with a (perhaps disquieting) change from the usual notation ( instead of , instead of ) you can consider the derivative of from first principles:

.

So the answer will be the derivative of f(a) with respect to a .... - Mar 1st 2009, 04:26 AMHallsofIvy
- Mar 1st 2009, 04:30 AMmr fantastic
- Mar 1st 2009, 05:06 PMthangbe
the limit is exists and the answer is.

but I don't know how to show for it.

- Mar 1st 2009, 05:31 PMmr fantastic
- Mar 1st 2009, 06:33 PMthangbe
I understand in your post #2 that why I get that answer. However my teacher didn't allows us to use that menthod :( thank you for you help sir.

- Mar 1st 2009, 06:41 PMmatheagle
Clearly there is a typo.

But once that is resolved, my favourite way to solve these type of limits is by multiplying by the conjugate. Not many people teach that these days. - Mar 1st 2009, 06:56 PMmr fantastic
- Mar 1st 2009, 07:05 PMmatheagle
I agree. I'm helping someone right now.

But substituting the math and typing tex at the same is tough for me.

I'm afraid I'll do a stupid calculation and I cannot edit after 15 minutes.

Leaving forever with a dumb math error.

That would be embarassing.

I really like the conjugate technique. - Mar 1st 2009, 07:18 PMthangbe
uhm... could you just simply tell me the procedure.? or just give a simple example. So that I can figure it out.... I was stuck in how to get x out of the squareroot value.

- Mar 2nd 2009, 01:49 AMmr fantastic
- Mar 2nd 2009, 06:07 AMthangbe
thank you so much for helping :)