Solving Exact Diff. Eq: Finding Integral Curves

  • Thread starter Thread starter fluidistic
  • Start date Start date
  • Tags Tags
    Curves Integral
fluidistic
Gold Member
Messages
3,929
Reaction score
272

Homework Statement


Find the solution to y'=\frac{y+x}{y-x} and graph the integral curves.

Homework Equations


Exact differential equation.

The Attempt at a Solution


I noticed it's an exact differential equation, I solved it implicitely. I reached that \frac{y^2 (x)}{2}-\frac{x^2}{2}-yx=\text{constant}. I've looked into wikipedia about the integral curves but I don't really know how to find them here. If I understood well, an integral curve is a solution to the DE, so here it would be any y(x) that satisfies the DE. But here I can't get y(x) explicitely, so how do I graph y(x)?... Any idea is welcome!
 
Physics news on Phys.org
Choose a number of specific values for the constant and graph those curves.
 
HallsofIvy said:
Choose a number of specific values for the constant and graph those curves.

Ah I see, thank you very much. I graph point per point, maybe I'm missing an obvious curve or something.
I take C=1. I set x=0 and I get y=\pm \sqrt 2. I graph this in the x-y plane. Now I set x=2 and I get a quadratic equation for y, which yields y= 2 \pm \sqrt {10}. So for a fixed C, there are 2 curves; maybe parabolas or hyperbolas.
 
Thread 'Use greedy vertex coloring algorithm to prove the upper bound of χ'
Hi! I am struggling with the exercise I mentioned under "Homework statement". The exercise is about a specific "greedy vertex coloring algorithm". One definition (which matches what my book uses) can be found here: https://people.cs.uchicago.edu/~laci/HANDOUTS/greedycoloring.pdf Here is also a screenshot of the relevant parts of the linked PDF, i.e. the def. of the algorithm: Sadly I don't have much to show as far as a solution attempt goes, as I am stuck on how to proceed. I thought...
Back
Top