Re: derivative

On Sun, 24 Apr 2005 13:58:24 -0600, Virgil
<ITSnetNOTcom#virgil@xxxxxxxxxxx> wrote:

>In article <Y7Sae.1992$pk5.339@fed1read02>, "vsgdp" <spam@xxxxxxxx>
>wrote:
>
>> If I have a function f(x, y), where x = x(t) and y = y(t), is this the
>> correct way to take the derivative wrt to t?
>>
>> d/dt( -x / (x^2 + y^2) )
>>
>> = [(x^2 + y^2)(-dx/dt) + x(2x(dx/dt) + 2y(dy/dt))] / (x^2 + y^2)^2
>>
>> ?
>
>Looks OK.

Almost, but the third term in the numerator is missing a factor of x.

--Lynn
.

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