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Question: Answered & Verified by Expert
The general solution of the differential equation x2+xyy'=y2 is
MathematicsDifferential EquationsJEE Main
Options:
  • A eyx=cx
  • B cy=e-yx
  • C e-yx=cxy
  • D e-2yx=cy
Solution:
1205 Upvotes Verified Answer
The correct answer is: cy=e-yx

Given that,

x2+xyy1=y2

x2+xydydx=y2
dydx=y2x2+xy 1

Let y=vx

Differentiating w.r.t. 'x'?

dydx=ddxvx

dydx=v+x·dvdx

y2x2+xy=v+x·dvdx

v2x2x2+xvx=v+xdvdx

v21+v=v+x·dvdx

v21+v-v=xdvdx

v2-v-v21+v=xdvdx

-v1+v=xdvdx

1xdx=-1+vv·dv

Integrating on both sides

1xdx=-(1+v)vdv

logx=-1vdv+vvdv

logx=-logv+v+logc

logx=-logyx+yx+logc

logx+logyx+logc=-yx

logx·yx·c=-yx

cy=e-yx

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