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Differential Equation Method Question

  • Thread starter jofree87
  • Start date
  • #1
38
0
dy/dx = (y-x)/(y+x)

I am suppose to solve this equation using substitution, but isn't it possible to solve this equation an easier way since it is an exact equation?

(y+x)dy - (y-x)dx = 0
 

Answers and Replies

  • #2
Gib Z
Homework Helper
3,346
5
It's not an exact ODE. The form is [tex]P(x,y)dy + Q(x,y) dx = 0[/tex] for exact ODE's, you didn't bring the negative factor in.
 
  • #3
24
0
dy/dx = (y-x)/(y+x)

I am suppose to solve this equation using substitution, but isn't it possible to solve this equation an easier way since it is an exact equation?

(y+x)dy - (y-x)dx = 0
[tex]\frac{dy}{dx}=\frac{y-x}{y+x}=\frac{y}{y+x}-\frac{x}{y+x}[/tex]

Use the substitution [tex]v=x+y[/tex].
 

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