A. 1:32

B. 32:1

C. 1:16

D. 16:1

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

If x is so small that x^{2} and higher powers of x may be neglected then (1-x)^{1/2}(1+x)^{2/3}/(1-x)^{1/2}