If , then the coefficient of xr in the expansion of , is
r2r
(2r - 1)2r
r22r + 1
(2r + 1)2r
D.
(2r + 1)2r
The coefficient of xr
If the coefficients of rth and (r + 1)th terms in the expansion of (3 + 7x)29 are equal, then r is equal to
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Suppose X follows a binomial distribution with parameters n and p, where 0 < p < 1. If is independent of n for every r, then p is equal to