Q38 / 90 · JEE Main 2022 (28 Jun Shift 2) · Mathematics

Let x=xy be the solution of the differential equation 2yexy2dx+y2-4xexy2dy=0 such that x1=0. Then, xe is equal to

  • A
    eloge2
  • B
    -eloge2
  • C
    e2loge2
  • Correct answer
    D
    -e2loge2

Solution

Given,

2yexy2dx+y2-4xexy2dy=0

2exy2ydx-2xdy+y2dy=0

2exy2y2dx-x·2ydyy+y2dy=0

Divide by y3

2exy2y2dx-x·2ydyy4+1ydy=0

2exy2dxy2+1ydy=0

Now integrating both side we get,

∫2exy2dxy2+∫1ydy=0

2exy2+lny+c=0

Given, 0,1 lies on it, 

So, 2e0+ln1+c=0⇒c=-2 

Hence required curve: 2exy2+lny-2=0

For xe

2exe2+lne-2=0  ⇒ x=-e2loge2

Hence, the correct answer is option: 'D'.

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