Let y = y ( x ) be the solution of the differential equation, x 2 + 1 2   d y d x + 2 x ( x 2 + 1 ) y =…

Let y=y(x) be the solution of the differential equation, x2+12 dydx+2x(x2+1)y=1 such that y0=0. If a y1=π32, then the value of a is
  1. 116
  2. 12
  3. 14
  4. 1

Solution

x2+12 dydx+2xx2+1y=1
dydx+2xx2+1y=1(x2+1)2
Which is a linear differential equation with integrating factor
I.F. = e2xx2+1dx=eln(x2+1)=x2+1
The solution of the given differential equation will be,
y.x2+1=x2+1.1x2+12dx=dxx2+1=tan-1x+c
Now, y0= 0 C=0 and y=1(x2+1)tan-1x
ay(1)=π32a=π/32π/8=14
a=116

Asked in: JEE Main 2019 (08 Apr Shift 1)

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