The correct option is A 16 sec32x−12sec 2x+c
∫tan32x sec 2x dx=∫(sec22x−1)sec 2x tan 2x dx
=∫(sec32x tan 2x−sec 2x tan 2x)dx
=∫sec32x tan 2x dx−∫sec 2x tan 2x dx ........ (i)
Now, we take ∫sec32x tan 2x dx
Put sec 2x=t⇒sec 2x tan 2x=dt2, then it reduces to
12∫t2dt=t36=sec32x6
From (i), ∫sec32x tan 2x dx−∫sec 2x tan 2x dx
=sec32x6−sec 2x2+c
Trick: Let sec 2x=t,then sec 2x tan 2x dx=12dt∴12∫(t2−1)dt=16t3−12t+c=16sec32x−12 sec 2x+c