Let x = x y be the solution of the differential equation 2 y + 2 log e y + 2 d x + x + 4 - 2 log e y + 2 d y…

Let x=xy be the solution of the differential equation 2y+2logey+2dx+x+4-2logey+2dy=0y>-1 with xe4-2=1. Then xe9-2 is equal to
  1. 3
  2. 49
  3. 329
  4. 103

Solution

Given,

2y+2logey+2dx+x+4-2logey+2dy=0

Let x+4=u, y+2=v

dx=du, dy=dv

So, the equation becomes,

2v lnvdu=-u-2 lnvdv

2v lnvdudv+u=2 lnv

dudv+12v lnv. u=1v

Which is a linear differential equation,

So, IF=e121v lnv=e12lnlnv=lnv12

Now solution of differential equation is given by,

u·lnv12=1v·lnv12dv

u·lnv12=23lnv32+c .......i

Now using given value, y=e4-2x=1

 v=e4 u=5

5·412=23·432+c

10=163+c

c=143

Now finding, y=e9-2v=y+2=e9

Now putting the value in equation i we get,

u·3=23×27+143=18+143

x+4=u=6+149

x=2+149=329

Asked in: JEE Main 2023 (15 Apr Shift 1)

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