The co-efficient of `x^(401)` in the expansion of `(1+x+x^(2)+.....+x^(9))^(-1),(|x| lt 1)` is

The co-efficient of x in the expansion of (1-x+2x^(2))^(11) is

The co-efficient of x^(11) in the expansion of (1+3x+2x^(2))^(6) is

The co-efficient of x^(2020) in the expansion of (1+x)(1-x)^(2020) is

Find the co-efficient of x^4 in the expansion of (2x^2+1/x)^20 .

If |x| lt 1 , then the coefficients of x^(n) in the expansion of (1 + x + x^(2) + x^(3) …)^(2) , is

Find the co-efficient of x^(5) in the expansion of (1+x^(2))^(5)(1+x)^(4)

The co-efficient of x^(-9) in the expansion of ((x^(2))/(2)-(2)/(x))^(9) is

If |x| lt 1 , then the coefficient of x^(5) in the expansion of (1+ 2x + 3x^(2) + ..........)^((-3)/2) is