Solving ((y^2)+xy+1)dx+((x^2)+xy+1)dy=0 Using Exact Equations

  • Thread starter TheFirstOrder
  • Start date
In summary, the conversation discusses solving the equation ((y^2)+xy+1)dx+((x^2)+xy+1)dy=0 using the method of exact equations. The problem arises when the partial derivatives are not equal to each other. The individual attempts at solving the problem are also mentioned, but the solution is not found.
  • #1
TheFirstOrder
3
0

Homework Statement



Solve

((y^2)+xy+1)dx+((x^2)+xy+1)dy=0

using the method of exact equations.

Homework Equations



I must use:

(N[tex]_{x}[/tex]-M[tex]_{y}[/tex])/(xM-yN)=F(xy)

The Attempt at a Solution



The problem that I'm having is that I can't get the required partial derivatives to be equal to each other. How do can I change it so that N[tex]_{x}[/tex]=M[tex]_{y}[/tex]?

When I started this problem initially, I got F(xy)=1, which is not right as 1 is not a function of xy (and I had forgotten to check that the partial derivatives were equal to each other) :P

Please help. It's my first time here.

And sorry, the superscripts are meant to be subscripts!
 
Physics news on Phys.org
  • #2
Since Nx is not equal to My, the equation isn't exact. Are you sure you copied the question correctly?
 
  • #3
ideasrule said:
Since Nx is not equal to My, the equation isn't exact. Are you sure you copied the question correctly?

Yes, that is the precise equation. And that's how I'm stuck.

Mx=2y+x
Ny=2x+y

I read things in my textbook that says I could times the original equation by a factor that would result in the two partial equations being equal, but that doesn't seem to work in this case. I'm completely clueless.
 

What is the first step in solving this exact equation?

The first step is to check if the equation is exact by checking if the partial derivatives of the coefficients with respect to the other variable are equal.

How do I find the integrating factor for this exact equation?

To find the integrating factor, divide the coefficient of dx by the coefficient of dy. This will give you the integrating factor, which can then be multiplied to both sides of the equation.

What is the next step after finding the integrating factor?

The next step is to multiply the integrating factor to both sides of the equation and then rearrange the terms to put them in the form of an exact equation (M(x,y)dx+N(x,y)dy=0).

What do I do after putting the equation in the form of an exact equation?

After putting the equation in the form of an exact equation, we can solve it by finding the total differential of the function F(x,y) where M(x,y)=∂F/∂x and N(x,y)=∂F/∂y. Then, we can integrate both sides to find the general solution.

Is there any other method to solve this exact equation?

Yes, another method is to use the method of separation of variables, where we separate the equation into two equations with only one variable each, and then solve each equation separately. The solutions can then be combined to find the general solution.

Similar threads

  • Calculus and Beyond Homework Help
Replies
2
Views
589
  • Calculus and Beyond Homework Help
Replies
6
Views
543
  • Calculus and Beyond Homework Help
Replies
5
Views
532
  • Calculus and Beyond Homework Help
Replies
25
Views
312
  • Calculus and Beyond Homework Help
Replies
2
Views
1K
  • Calculus and Beyond Homework Help
Replies
2
Views
531
  • Calculus and Beyond Homework Help
Replies
4
Views
838
  • Calculus and Beyond Homework Help
Replies
6
Views
1K
Replies
13
Views
1K
  • Calculus and Beyond Homework Help
Replies
8
Views
1K
Back
Top