Q.

The constant term in the expansion of (x2-1x2)16 is

1 C816  
2 C716  
3 C916  
4 C1016  

Ans.

(1)

Let (r+1)th term be the constant term in the expansion of (x2-1x2)16

∴  Tr+1=Cr16x2r(-1x2)16-r

=(-1)16-r Cr16x2r·x-32+2r=(-1)16-r Cr16x4r-32

For constant term, 4r-32=0⇒r=8

∴  T9=(-1)8 C816=C816