The coefficient of x3y4z5 in the expansion of (xy + yz + xz)6 is
70
60
50
None of these
B.
60
If the general term in the above expanssion contains x3y4z5, then
r + t = 3, r + s = 4 and s + t = 5
Also, r + s + t = 6
Solving these equations, we get
r = 1, s = 3, t = 2
If the coefficients of rth and (r + 1)th terms in the expansion of (3 + 7x)29 are equal, then r is equal to
14
15
18
21
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