Solution of (1 + xy) y dx + (1 - xy) x dy = 0 is
log xy + 1xy = c
log xy=c
log xy - 1xy = c
None of these
Differentiating the given expression:
(1 + xy) y dx + (1 - xy) x dy = 0
This expression can be written as
ydx+xyydx +xdy-xyxdy=0
Solving further we get,
ydx+xdy+xyydx-xdy=0⇒ dxy+xy2ydx-xdyxy=0 dxy=ydx+xdy⇒ dxy+xy2dxx-dyy=0Dividing by xy2⇒ 1xy2d(xy)+dxx-dyy=0⇒ xy-2d(xy)+dxx-dyy=0⇒ xy-1-1+logx-logy=c ∵xy-2d(xy)=xy-1-1⇒ logxy-1xy=c
Therefore, option (C) is the correct answer.