The number of terms in the expansion of (x2+1+1x2)n,n∈ N, is
2n
3n
2n+1
3n+1
[1+(x2+1x2)]n = nCo + nC1(x2+1x2) + nC2 (x2+1x2)2 + nC3 (x2+1x2)3 .............nCn (x2+1x2)n
there 2 distinct terms corresponding to each factor ⇒ hence total number of terms 2n+1.
The (n+1)th term from the end in the expansion of (2x−1x)3n is: