A. 456

B. 365

C. 256

D. 425

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

The 4^{th} term of ^{6}(x+2/x^{2})^{6 }is