first order differential equation: x dy + y d = y dy

cheffy

Junior Member
Joined
Jan 10, 2007
Messages
73
I started with

\(\displaystyle \
xdy + yd = ydy
\\)

and simplified it to

\(\displaystyle \
y' + \frac{y}{{x - y}} = 0
\\)

but now I don't know how to separate that y out to get P(x). Help! Thanks.
 
Let y = mx ==> dy/dx = (dm/dx)x + m (differentiating both sides with respect to x)

Proceed to replace all y's with "mx" and it should become a nice separable equation.
 
Are you SURE you wrote the peoblem down correctly? Did it REALLY use a parameter of "d"? If so, you seem to have lost it somewhere along the road. If not, then what is that second term?
 
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