The general solution of the differential equation 1 + x 2 + y 2 + x 2 y 2 + x y d y d x = 0 (where C is a…

The general solution of the differential equation 1+x2+y2+x2y2+xydydx=0 (where C is a constant of integration)
  1. 1+y2+1+x2=12loge1+x2-11+x2+1+C
  2. 1+y2-1+x2=12loge1+x2-11+x2+1+C
  3. 1+y2+1+x2=12loge1+x2+11+x2-1+C
  4. 1+y2-1+x2=12loge1+x2+11+x2-1+C

Solution

1+x21+y2+xydydx=0

Integrating,

2y21+y2dy=-1+x2x1+x2dx
1+y2=-x1+x2dx-xx21+x2dx

Put 1+x2=tx2=t2-1 to solve RHS 2nd integration, 

1+y2=-1+x2-tt2-1tdt
1+y2+1+x2=-1t2-1dt
1+y2+1+x2=12ln1+x2+11+x2-1+C

Asked in: JEE Main 2020 (06 Sep Shift 1)

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