A. 51C5

B. 9C5

C. 31C6-21C6

D. 30C5+20C5

The coefficient of x^{7} in (ax^{2}-1/bx)^{11} is equal to the coefficient of x^{-7} in (ax-1/bx^{2}) then ab=

The number of non zero terms in the expansion of (8+2)^{101} - (8-2)^{101} is

The coefficients of three consecutive terms in the expansion of (1+x)^{n} are in the ratio 1:7:42, then n=

Which term of (2x-3y)^{12} when x=1, y=5/2 numerically greatest?

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