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**KiWoonG****Guest**

Hi everyone

I am very confused in differentiating in fractions

x^2

f(x) = _______

1+x^2

i know how to differentiate the numerator but not denominator

how do you differentiate the bottom???

*** i already know that u'v-v'u formula and i dont mean by that..

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v^2

i wanna know how to differentiate separately, numerator and denominator

Thank you

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 21,312

f(x) = x²/(1+x²)

f(x) = x²(1+x²)-¹

Now, use the uv method:- u'v + uv'

f'(x) = 2x(1+x²)-¹ + x²(-1)(1+x²)-²(2x)

This is because you didn't want to use u/v = (u'v - uv')/v²

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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**kylekatarn****Member**- Registered: 2005-07-24
- Posts: 445

I don't know why you are avoiding the formula....

Anyway, **just for fun**, you can differentiate f(x) using my loooong method

(in pratical problems use Ganesh's method.)

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**Flowers4Carlos****Member**- Registered: 2005-08-25
- Posts: 106

i would not wanna try it ur way kylekatarn

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