Find the sum of the coefficients of all the integral powers of x in the expansion of `(1+2sqrt(x))^(40)`.

Show that the coefficient of the middle term in the expansion of (1+x)^(2n) is equal to the sum of the coefficients of two middle terms in the expansion of (1+x)^(2n-1)

Find the coefficient of x^4 in the expansion of (1-x^2)^n

Find the coefficient of x^4 in the expansion of (1+x)^n(1-x)^n

The sum of the coefficients in the expansion of (1+2x-x^2)^(20) is

Find the coefficient of x^20 in the expansion of (3x^3-2/x^2)^40