Variable Separation: Solving x^2y'=1-x^2+y^2-x^2y^2

In summary, the conversation was about trying to solve the differential equation x^2y'=1-x^2+y^2-x^2y^2 by separating the y terms on one side and the x terms on the other. The solution involved factorizing (1-x^2) and (1+y^2) to simplify the equation. The conversation ended with the realization that the easiest method was the correct answer.
  • #1
erok81
464
0

Homework Statement



[tex]x^2y'=1-x^2+y^2-x^2y^2[/tex]

Homework Equations



n/a

The Attempt at a Solution



I am trying to separate the y terms on one side and the x terms on the other so I can solve this differential equation. I've tried everything I can think of, but cannot get them on their respective sides.

Any hints starting in the right direction?
 
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  • #2
erok81 said:

Homework Statement



[tex]x^2y'=1-x^2+y^2-x^2y^2[/tex]

Homework Equations



n/a

The Attempt at a Solution



I am trying to separate the y terms on one side and the x terms on the other so I can solve this differential equation. I've tried everything I can think of, but cannot get them on their respective sides.

Any hints starting in the right direction?

[tex]x^2y'=(1-x^2)+(1-x^2)y^2[/tex]
 
  • #3
That was actually what I tried in the beginning.

Next I tried dividing everything by x^2 to get y' alone. Then tried subtracting (1-x^2)y^2. Then spent the next ten minutes moving things back and forth until I started over.

This is really stupid, but say I am dividing both sides by y^2. It has to go into all three pieces, correct? It doesn't just get canceled out one the one side, does it?
 
  • #4
hmm, you can factorize [tex]
(1-x^2)
[/tex]

[tex]
(1-x^2)(1+y^2)
[/tex]

;P
 
  • #5
Haha, thanks.

I love spending forever on some problems, only to find out the easiest method is the correct answer. I always get stuck on the easiest ones. I don't get it. :smile:[tex](1-x^2)(1+y^2) = 1-x^2+y^2-x^2y^2[/tex] aka the original problem. I don't think they make factoring problems easier than that.:-p
 
Last edited:

Related to Variable Separation: Solving x^2y'=1-x^2+y^2-x^2y^2

1. What is Variable Separation?

Variable Separation is a method used to solve differential equations by separating the variables on opposite sides of the equation. This allows for each variable to be integrated separately, making the equation easier to solve.

2. How is Variable Separation used to solve x^2y'=1-x^2+y^2-x^2y^2?

In order to use Variable Separation to solve this equation, we must first rearrange it to the form y' = f(x)g(y). In this case, we can rewrite the equation as y' = (1-x^2)/(x^2(1-y^2)). Then, we can separate the variables to get (1-y^2)dy = (1-x^2)/x^2 dx. Integrating both sides and solving for y will give us the solution to the original equation.

3. What is the purpose of using Variable Separation to solve differential equations?

The purpose of using Variable Separation is to make solving differential equations easier. By separating the variables, we can integrate each side individually, which is often simpler than trying to solve the equation as a whole. This method is particularly useful for non-linear equations, like the one given in this question.

4. Are there any limitations to using Variable Separation?

Yes, there are limitations to using Variable Separation. This method can only be used for first-order, separable differential equations. Additionally, it may not always be possible to separate the variables, in which case another method must be used to solve the equation.

5. What are some other methods for solving differential equations?

There are several other methods for solving differential equations, including substitution, integrating factors, and series solutions. Each method has its own advantages and limitations, and the most appropriate method to use will depend on the specific equation being solved.

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