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#1 2005-08-30 19:04:15

KiWoonG
Guest

Differentiating

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..
                                    ---------
                                      v^2   
i wanna know how to differentiate separately, numerator and denominator

Thank you

#2 2005-08-30 21:38:56

ganesh
Moderator

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Re: Differentiating

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 big_smile

Character is who you are when no one is looking.

#3 2005-08-31 09:50:53

kylekatarn
Power Member

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Re: Differentiating

I don't know why you are avoiding the formula....
Anyway, just for fun, you can differentiate f(x) using my loooong method

http://adsl.xl.pt/kylekatarn/img/diff.gif
(in pratical problems use Ganesh's method.)

#4 2005-08-31 11:59:00

Flowers4Carlos
Full Member

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Re: Differentiating

i would not wanna try it ur way kylekatarn wink

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