The term independent of x in the expansion of (1+x)n(1+1x)n is
Consider given the expression,
⇒(1+x)n(1+1x)n
⇒(1+x)n(1+x)nxn
⇒x−n(1+x)2n
So,
Required term independent of x=coefficient of x0 inx−n(1+x)2n
=coefficient of xn in (1+x)2n =2nCn
Hence, this is the answer.