Q.

The term independent of x in the expansion of (32x2-13x)6 is

1 512  
2 125  
3 56  
4 none of these  

Ans.

(1)

(32x2-13x)6

Tr+1=Cr6(32x2)6-r(-13x)r=Cr6(32)6-r(-13)rx12-3r

Put  12-3r=0  ⇒  r=4

∴  Term independent of x is T5=C46(32)2(-13)4=512