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Mathematics 8 Online
OpenStudy (anonymous):

Solve this differential equations

OpenStudy (anonymous):

Solve \[xe^{2x} \frac{ dy }{ dx } + e^{2x} (2x+1) y \]

OpenStudy (anonymous):

y not solve using seperation

OpenStudy (anonymous):

@Outkast3r09 Yes, of course, i really know.., it is use linear equations method, isn't it?

OpenStudy (anonymous):

It's a separable equation, which means it can be written in the form N(y) dy = M(x) dx Rewrite the equation to get it in this form, and integrate both sides

OpenStudy (anonymous):

Im learning too, is this right? \[\frac{ dx }{ xe ^{2x} }= e ^{2x}y dy (2x+1)\]

OpenStudy (anonymous):

What you want do do is have only y's on the side of dy, and only x's on the side of dx. Here are some example problems http://tutorial.math.lamar.edu/Classes/DE/Separable.aspx which will give you a good general idea of how to tackle the problem :) \[x e^{2x} \frac{dy}{dx} + e^{2x}(2x + 1)y = 0\] \[x e^{2x} dy = - e^{2x}(2x + 1)y dx\] \[\frac{1}{y}dy = -\frac{-e^{2x}(2x + 1)}{xe^{2x}}dx\] Then integrate both sides :)

OpenStudy (anonymous):

Btw \[\frac{-e^{2x}(2x + 1)}{x e^{2x}}\] can be simplified to: \[-\frac{1}{x} - 2\]

OpenStudy (anonymous):

So what you get is: \[\int\limits_{}^{} \frac{1}{y} dy = \int\limits_{}^{} (- \frac{1}{x} - 2) dx\] I'll leave it to you to solve it

OpenStudy (anonymous):

You can probably use linear equations to solve it also... The whole point of Diff. Equations is to find multiple ways to solve the same problem

OpenStudy (anonymous):

first start off by dividing by \[xe^2x\]

OpenStudy (anonymous):

\[\frac{dy}{dx}+\frac{e^{2x}(2x+1)}{xe^{2x}}=0\]

OpenStudy (anonymous):

\[ \frac{dy}{dx}+\frac{(2x+1)}{x}=0\]

OpenStudy (anonymous):

now find the integration factor \[e^{\int{p(x)dx}}=e^{\int{\frac{2x+1}{x}dx}}\]

OpenStudy (anonymous):

\[e^{\int{2+\frac{1}{x}}dx}\]

OpenStudy (anonymous):

\[e^{2x-\frac{1}{x^2}}\]

OpenStudy (anonymous):

Isn't it\[\int_{}^{} (2 + \frac{1}{x}) dx = 2x + \ln |x| \]

OpenStudy (anonymous):

Nice @Outkast3r09 and @Meepi., I think.., in order to satisfy the equation: \[\frac{ dy }{ dx } + p(x)y = g(y)\] then the original equation becomes: \[x^{e^{2x}} \frac{ dy }{ dx } + e^{2x} 2xy+e^{2x} = 0 \] \[x^{e^{2x}} \frac{ dy }{ dx } + e^{2x} 2xy = -e^{2x}\] \[\frac{ dy }{ dx } + \frac{ e^{2x} 2xy }{ x^{e^{2x}} } = -\frac{ e^{2x} y }{ x^{e^{2x}} }\] So P(x) = \(\frac{ e^{2x} 2x}{ x^{e^{2x}}}\) and g(y) =\(-\frac{ e^{2x}y }{ x^{e^{2x}}} \) Hbu???

OpenStudy (anonymous):

hbu @nubeer ???

OpenStudy (nubeer):

xe^2x (dy/dx) + e^2x ( 2x+1)y = 0 right is this the question? i might take e^2x common first .. and then divide the whole equation by it

OpenStudy (anonymous):

yes., of course

OpenStudy (nubeer):

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