Let α x = exp x β y γ be the solution of the differential equation 2 x 2 y d y - 1 - x y 2 d…

Let αx=expxβyγ be the solution of the differential equation 2x2ydy-1-xy2dx=0, x>0,y2=loge2. Then α+β-γ equals :
  1. 1
  2. -1
  3. 0
  4. 3

Solution

Given the solution of differential equation,

αx=exβ·yγ......(1)

Now calculating the solution of differential equation, 

2x2ydydx=1-xy2

Let y2=t2dydx=dtdx

 x2dtdx=1-xt

dtdx+tx=1x2 .....(2)

Above differential equation is linear in t

We know solutions of differential equation of the form dydx+Py=Q is given by,

y.ePdx=Q.ePdx+C      (ePdx=I.F.)

Now calculating, I.F.=e1xdx=elnx=x

Therefore, the solution of equation 2 is given by,

t.x=1x2·xdx+C

y2·x=lnx+C

 y(2)=ln2

  2.ln2=ln2+CC=ln2

Hence, solution is xy2=lnx+ln2

 xy2=ln2x

 2x=ex·y2......(3)

On comparing equations 1 and 3 we get,

 α=2,β=1,γ=2

 α+β-γ=1

Asked in: JEE Main 2023 (01 Feb Shift 2)

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