Help solving this diff equation please!

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Apr 9th 2008, 10:22 AM
Richyie

Help solving this diff equation please!

we have

dv/dx = v-x^2+1 / x

then how do we deduce from that:

d(v/x)/dx = -1 + 1/x^2 ? ?

thanks
Apr 9th 2008, 10:30 AM
topsquark

Quote:

Originally Posted by Richyie

we have

dv/dx = v-x^2+1 / x

then how do we deduce from that:

d(v/x)/dx = -1 + 1/x^2 ? ?

thanks

Please use parenthesis!!

$\frac{d}{dx} \left ( \frac{v}{x} \right ) = \frac{\frac{dv}{dx} x - v}{x^2}$

$= \frac{(v - x^2 + 1) - v}{x^2} = \frac{-x^2 + 1}{x^2} = -1 + \frac{1}{x^2}$

For the record:
v-x^2+1 / x is
$v - x^2 + \frac{1}{x}$

-Dan
Apr 9th 2008, 10:45 AM
Richyie

yep i meant (v-x^2+1) / x sorry
thanks :)

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