Q36 / 90 · JEE Main 2023 (06 Apr Shift 1) · Mathematics

Let Ix=∫x2x sec2+tanx(x tanx+1)2dx If I0=0, then Iπ4 is equal to

  • A
    loge(π+4)216+π24(π+4)
  • B
    loge(π+4)216-π24(π+4)
  • Correct answer
    C
    loge(π+4)232-π24(π+4)
  • D
    loge(π+4)232+π24(π+4)

Solution

Given that Ix=∫x2x sec2x+tanx(x tanx+1)2dx

Apply Integration by parts.

∫fxgxdx=fx∫gxdx-∫f'x∫gxdxdx

=x2∫x sec2x+tanx(x tanx+1)2dx-∫dx2dx∫x sec2x+tanx(x tanx+1)2dxdx

Let xtanx+1=p

⇒x sec2x+tanxdp=dx

=x2∫dpp2-∫2x∫dpp2dx

=-x2(x tanx+1)+∫2xx tanx+1dx

Let I1=2∫xx tanx+1dx

=2∫x cosxx sinx+cosxdx

Let x sinx+cosx=t

⇒(x cosx+sinx-sinx)dx=dt

⇒(x cosx)dx=dt

=2∫dtt=2logt+c

=2log|x sinx+cosx|+c

∴∫x2xsec2x+tanx(xtanx+1)2dx

=-x2x tanx+1+2log|x sinx+cosx|+c

But I(0)=0

⇒c=0

Also,Iπ4=-π42π4×1+1+2log12π4+12

=loge(π+4)232-π24(π+4)

Hence, this is the correct option.

Hence, the correct answer is option: 'C'.

Relevant Questions