MHT CET20242 May 2024Morning ShiftMathematicsDifferential EquationsActual
If x ~d y ~d x =y( y- x+1) , then general solution of this equation is
Options
- A( x y )= c y , where c is a constant of integration.
- B( x y )=c x , where c is a constant of integration.
- C( y x )= cy , where c is a constant of integration.
- D( y x )= c x , where c is a constant of integration:
Correct answer
D. ( y x )= c x , where c is a constant of integration:
Step-by-step solution
aligned & x ~d y ~d x =y( y- x+1) . & d y ~d x = y x [ ( y x )+1 ] & Put v = y x & y= v x & ~d y ~d x = v +x ~d v ~d x & From (i) aligned aligned & v +x ~d v ~d x = v ( v +1) & v +x ~d v ~d x = vlog v + v & x ~d v ~d x = v v & 1 v v d v= d x x aligned Integrating on both sides, we get 1 vlog v dv = d x x aligned & ( v )= x+ c ₁ & ( v )= x+ c where, c ₁= c & ( v )= (x c ) & v =x c & ( y x )= c x aligned