A. (3,4,1)

B. (4,1,3)

C. (3,-4,-1)

D. (-4,1,3)

The coefficient of x^{6} in (1+x+x^{2}+x^{3}+x^{4}+x^{5})^{6} is

The ratio of the coefficient of x^{15} to the term independent of x in (x^{2}+2/x)^{15} is

The number of non zero terms in the expansion of (a+b)^{20} – (a-b)^{20} is

^{m}C_{r}+^{ m}C_{r-1}^{n}C_{1}+^{m}C_{r-2.}^{ n}C_{2}+………..+ ^{n}C_{r} =

Sum of the last 20 coefficients in the expansion of (1+x)^{39}, when expanded in ascending powers of x, is