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Differential Equations 17 Online
OpenStudy (anonymous):

answred

OpenStudy (anonymous):

to find y any method

OpenStudy (anonymous):

bernoulli equation or homogeneous

OpenStudy (anonymous):

can you help me @.Sam.

sam (.sam.):

\[xdx + ( y -2x)dy= 0\] \[xdx=-(y-2x)dy \\ -\frac{x}{y-2x}=\frac{dy}{dx}\] --------------------------------------- Try using y=vx Then \[\frac{dy}{dx}=v+x\frac{dv}{dx}\]

sam (.sam.):

Replace the y and \(\frac{dy}{dx}\) to v and the one given above \[-\frac{x}{vx-2x}=v+x\frac{dv}{dx} \\ \frac{1}{2-v}=v+x\frac{dv}{dx}\]

OpenStudy (anonymous):

yes then?

OpenStudy (anonymous):

the numerator can break it for the denomentor?

sam (.sam.):

Then set all v into the other side \[\frac{1-2v+v^2}{(2-v)x}=\frac{dv}{dx} \\ \frac{(2-v)x}{1-2v+v^2}=\frac{dx}{dv} \\ \int\limits \frac{(2-v)}{1-2v+v^2} dx=\int\limits \frac{1}{x}dx\]

sam (.sam.):

Should be dv \[\int\limits\limits \frac{(2-v)}{1-2v+v^2} dv=\int\limits\limits \frac{1}{x}dx\]

OpenStudy (dumbcow):

i think you get stuck here though...no way to solve for "v" the integral gives a fraction and a log

OpenStudy (anonymous):

i think we can use here synthetic division

OpenStudy (anonymous):

my Im right?

OpenStudy (dumbcow):

@melmel , no that only works if the "2-v" was in denominator

OpenStudy (dumbcow):

turns out you can't solve for "y" directly http://www.wolframalpha.com/input/?i=y%27%28x%29+%3D+x%2F%282x-y%28x%29%29

OpenStudy (anonymous):

can you help me to solve and to prove that?

OpenStudy (dumbcow):

@.sam, already did but you cant go any further just sub in y/x for v

OpenStudy (anonymous):

so what is my final answer?

OpenStudy (dumbcow):

i dunno depends on the instructions...ther is no "y =" answer

OpenStudy (anonymous):

CAN YO HELP ME @zepdrix

OpenStudy (anonymous):

coefficients by division?

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