Greates Binomial coefficient(or Middle terms) (1) If n is even, then there is only one middle term which (h/2 + 1) th term i.e. Tn/2 + 1 = n Cn/2 X n/2 and nCn/2 is greatest bionomial coefficient (2) If n is each them trere are two middle terms which are th and th terms i.e = a (n+1)/2 b(n-1)/2 and And, are greatest bionoimial ccoefficients Numarically Greatest term of Bionmial expansion (a + x)n = Co an + C1 an-1 x.........+ Cn-1axn-1 + Cnxn. The numerically greatest term will be Tr+1 where r = .... If itself is a natural number then Tr = Tr+1 both are numerically greatest terms. Why ?
If for given a, x and n then So, when  Illustration 3 Show that middle term in the expansion of (1 + x)2n is img........... where n isa +ve integer. Ans This number of terms in expassion of (1 + x)2n is 2n + 1 (odd) So, its middle term is (n + 1)th term. Required Term = Tn+1 = 2n Cn xn = xn = xn = xn. = xn = = 2n xn Illustration 4 find the greatest term in the expansion of Ans Let us find r = So, r = = = 7
Tr+1 = T8 is greatest term Now T8 = 20 C7 = Summation of series of Bionomial co-efficients. Series of Bionomia cofficients cn be umme by uing methods like by taaking prouct o expnion of two bionomial by differentiating bionomial expansion, integraating bionomial expansion by equating real and imaginory part of a eries etc. (1) Sum of sevies by taking product o expnsions of two bionomials if we find the product of binomial coefficients in tnhe sevies then this method can be used .
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