AP EAMCET2006MathematicsDifferential Equations
The solution of (x^2+y^2 ) d x=2 x y d y is :
Options
- Ac (x^2-y^2 )=x
- Bc (x^2+y^2 )=x
- Cc (x^2-y^2 )=y
- Dc (x^2+y^2 )=y
Correct answer
A. c (x^2-y^2 )=x
Step-by-step solution
x^2+y^2 2 x y = d y d x Put y=v x and d y d x =v+x d v d x v+x d v d x = x^2+v^2 x^2 2 x^2 v v+x d v d x = 1+v^2 2 v x d v d x = 1+v^2-2 v^2 2 v 2 v 1-v^2 d v= 1 x d x - (1-v^2 )= x+ c - ( x^2-y^2 x^2 )= x+ c - (x^2-y^2 )+2 x= x+ c x= c+ (x^2-y^2 ) x=c (x^2-y^2 )