In the expansion of `(x-1)(x-3)(x-5).........(x-99)`, the coefficient of `x^49` is.

In the expansion of (x-1) (x-2) …(x-18) , the coefficient of x^(17) is

In the expansion of (1+x+x^(2)+...oo)^(3) the coefficient of x^(n) is

If sum of the coefficients in the expansion of (x+1/x)^(n) is 128, then coefficient of x in the expansion of (x+1/x)^(n) is

If in the expansion of (x^3-1/x^2)^n the sum of the coefficients of x^5 and x^10 is 0 , then the coefficient of :the third term