A. 315+1/2

B. 315+2/2

C. 315-1/2

D. none

If |x| <1/2, then the coefficient of x^{r }in the expansion of (1+2x) / (1-2x)^{2} is :

If nεN, n is odd then n(n^{2}-1) is divisible by

If the middle term of (1+x)^{2n }is 1.3.5...(2n-1)k/n! then k=

The general term of (2a-3b)^{-1/2 }is

The coefficient of x^{r} in (1+x)^{2}/(1-2x)^{3} is