The term void of x  in the expansion of (x3+3x2)10  is

Given expansion is  (x3+3x2)10 then we have to find independent term General term in the expansion Tr+1= nCr xn−r ar Tr+1= 10Cr(x3)10−r(3x2)r (simplication of x  terms and constant)          = 10Crx10−r2−2r 3r−5 ( these x  term compare with x0 )This term is independent of x  if x10−r2−2r=x0 powers are equal then we get  i.e. if r=2  henceT2+1= 10C2 (x3)10−2 (3x2)2⇒T3= 10C2 (x3)8 (3x2)2    = 10C2 3−3  =10×92×127=53 (∴ nCr=n!(n−r)!r!)