Q.

Let y = y(x) be the solution of the differential equation (1+x2) dydx+y=etan-1x, y(1) = 0. Then y(0) is                   [2024]

1 12(eπ/2-1)  
2 12(1-eπ/2)  
3 14(eπ/2-1)  
4 14(1-eπ/2)  

Ans.

(2)

We Have, (1 + x2) dydx + y = etan-1x

  dydx + y1 + x2 = etan-1 x1 + x2

IF = e11 + x2 dx = etan-1 x

  yetan-1 x = etan-1 x1 + x2·etan-1 x dx + c

Let tan-1 x = t

  11 + x2 dx = dt      yet = e2t dt + c

  yet = e2t2 + c      yetan-1 x = e2 tan-1 x2 + c

Since y(1) = 0

  0eπ/4 = eπ/22 + c      c = -eπ/22

  y = etan-1 x2 - eπ/22etan-1 x

  y(0) = 12 - eπ/22 = 1 - eπ/22