some important pts. while u r doing binomial theorem.............
1)
nc
r is maximum for a given value of n

r
a) wen n is even ............r = n/2
b)wen n is odd ..............r = n+1/2 or n-1/2
2)co-eff. of terms equidistant frm the beginning and end in the expansion of (x + a)n are equal
3)(1+x)-k = k + r - 1cr . xr
4)no. of dissimilar terms in the expansion of (x + y + z)n is ( n + 1 )( n + 2 ) / 2
5)In the expansion of (x + a)n (x , a >0 ) the greatest term is Tm+1 where m is the largest +ive integer 'r' satisfying [n-r+1.a] / rx >= 1
6)if x > 0 , then the greatest co-eff. in the expansion of (1+x)n is
a)ncn/2 if n is even
b)nc(n-1)/2 or nc(n+1)/2 if n is odd
7 ) If the index 'n' is even then there is only 1 middle term in the expansion of (x+a)n i.e = (n+2)/2 th term
8)If the index 'n' is odd, then there are 2 middle terms in the expansion of (x+a)n i.e = (n+1)/2th and (n+3)/2th terms
9)sum of co-eff. in the expansion of (x+a)n is 2n
10)sum of co-eff. of odd terms = sum of coeff of even terms i.e 2n-1
original
no copy paste
wrote myself
hope these helps......................