how to solve this kind of problem in linear differential equation?
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OpenStudy (erikaxx):
problem is \[x \frac{ dy }{ dx } = y + x^3 +3x^2 - 2x\]
OpenStudy (loser66):
Where are you stuck?
OpenStudy (erikaxx):
\[\frac{ dy }{ dx } = \frac{ y }{ x } + x^2 + 3x - 2\]
OpenStudy (loser66):
yup
OpenStudy (erikaxx):
there, now i cant identifies the Q(x) and p(x)
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OpenStudy (loser66):
\(\dfrac{dy}{dx}-\dfrac{y}{x}=x^2+3x-2\)
OpenStudy (erikaxx):
so the p(x) is x
OpenStudy (loser66):
-1/x
OpenStudy (erikaxx):
ah, and the remaing terms is the q(x)
OpenStudy (loser66):
yup
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OpenStudy (erikaxx):
so IF is \[\int\limits e ^{\frac{ -1 }{ x }dx}\]
OpenStudy (erikaxx):
so e ^ -lnx
OpenStudy (loser66):
IF = 1/x
OpenStudy (loser66):
You always make mistake at this. It is NOT \[\int e^{-1/x} dx\]
OpenStudy (loser66):
\[IF = e^{\int p(x) dx}\]
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OpenStudy (erikaxx):
yes so the soln is now \[(\frac{ 1 }{ x })y = [x^2 +3x - 2 ](x) (\frac{ 1 }{ x }) dx + c\]
OpenStudy (loser66):
Again, you always make mistake at (x) from the RHS, where does it come from?
\[(\frac{ 1 }{ x })y = [x^2 +3x - 2 ]\color{red}{(x)(?)} (\frac{ 1 }{ x }) dx + c\]
OpenStudy (erikaxx):
what x
OpenStudy (loser66):
the red one
OpenStudy (erikaxx):
ah, i just putted it sorry its Q(X) only
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