Q.

Let the solution curve y=y(x) of the differential equation dydx-3x5tan-1(x3)(1+x6)3/2y=2xexp{x3-tan-1x3(1+x6)} pass through the origin. Then y(1) is equal to      [2023]

1 exp{4+π42}  
2 exp{4-π42}  
3 exp{1-π42}  
4 exp{π-442}  

Ans.

(2)

Given differentiate equation is

dydx-3x5tan-1(x3)(1+x6)3/2y=2xexp{x3-tan-1x3(1+x6)},

Which is in the form dydx+Py=Q

Here, P=-3x5tan-1(x3)(1+x6)3/2, Q=2xexp{x3-tan-1x31+x6}

Let I=-∫3x5tan-1x3(1+x6)3/2dx

Put x3=tanθ ⇒ 3x2 dx=sec2θdθ

I=-∫tanθ·θsec3θ×sec2θ dθ=-∫θ·sinθdθ

=-[θ∫sinθdθ-∫(∫sinθdθ)dθ]

=-[-θ·cosθ+sinθ]=-[x31+x6-tan-1(x3)·11+x6]

∴    I.F.=e∫pdx=eI

Solution of the D.E. is

y·eI=∫eI·2x·exp{x3-tan-1(x3)1+x6}dx

=∫2x·e-x3+tan-1(x3)1+x6·ex3-tan-1(x3)1+x6dx

=∫2x·dx=x2+c                 ∴    yeI=x2+c

∴  y=x2exp{-tan-1(x3)+x31+x6}+c exp{x3-tan-1(x3)1+x6}

This curve passes through the origin.

So, 0=0+c⇒c=0

The required solution is

         y(x)=x2exp{x3-tan-1(x3)1+x6}

At x=1    y(1)=exp(1-π42)=exp(4-π42)