Help Solving a differential equation

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Homework Help Overview

The discussion revolves around solving a differential equation of the form (x+2y)y' = y. Participants explore various methods for approaching the problem, including substitution and rewriting the equation.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • The original poster attempts substitution with v = (x + 2y) but finds it does not lead to a separable or first-order linear equation. Some participants suggest dividing by y and manipulating the equation to find a linear form. Others propose rewriting the equation to check for exactness and consider integrating factors.

Discussion Status

Participants are actively exploring different methods to approach the differential equation. Suggestions include checking for exactness and using integrating factors, indicating a productive direction in the discussion without reaching a consensus on a single method.

Contextual Notes

There is a mention of the equation not being exact and the need for an integrating factor, highlighting the complexity of the problem. The original poster's uncertainty about the substitution method also points to potential gaps in information or understanding.

Giuseppe
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Hello, i was wondering if someone can help me along with solving this differential equation.(x+2y)y'=y

I believe you use substitution. Right now I am setting my substitution to
v=(x+2y), but then when i follow through with my work, it doesn't simplify down to a seperable or first order linear equation. Am I doing something wrong?

-giuseppe
 
Last edited:
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try this should make a nice linear in terms of x

divide the left side by y

then divide 1 by y' and you should end up with a linear in terms of x
 
Rewrite this in the form M(x,y)dx + N(x,y)dy = 0. Then, check if this is an exact differential equation. If not, can you find an integrating factor to make it exact?

I don't think substitution works here. It's just not separable.
 
This is NOT an exact equation either.

I like Valhalla's suggestion. You can rewrite it as

y(dx/dy)= x+ 2y which is a LINEAR equation for x as a function of y. If you really need y as a function of x, invert the function.
 
I didn't say it was exact... I said he should check if it was exact. :smile:

It's easy enough to make it exact with an integrating factor though.

There is more than one way to skin a cat...
 

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