$(2n + 1) (2n + 3) (2n + 5) ....... (4n - 1)$ is equal to :
$\frac{{(4n)\,\,!}}{{{2^n}\,.\,\,(2n)\,\,!\,\,(2n)\,\,!}}$
$\frac{{(4n)\,\,!\,\,\,n\,\,!}}{{{2^n}\,.\,\,(2n)\,\,!\,\,(2n)\,\,!}}$
$\frac{{(4n)\,\,!\,\,\,n\,\,!}}{{(2n)\,\,!\,\,(2n)\,\,!}}$
$\frac{{(4n)\,\,!\,\,\,n\,\,!}}{{{2^n}\,\,!\,\,(2n)\,\,!}}$
The value of ${\sum\limits_{r = 1}^{19} {\frac{{{}^{20}{C_{r + 1}}\left( { - 1} \right)}}{{{2^{2r + 1}}}}} ^r}$ is
The sum of the coefficients in the expansion of ${(1 + x - 3{x^2})^{2163}}$ will be
In the expansion of ${(x + a)^n}$, the sum of odd terms is $P$ and sum of even terms is $Q$, then the value of $({P^2} - {Q^2})$ will be
If the sum of the coefficients in the expansion of ${(1 - 3x + 10{x^2})^n}$ is $a$ and if the sum of the coefficients in the expansion of ${(1 + {x^2})^n}$ is $b$, then
If $C_r= ^{100}{C_r}$ , then $1.C^2_0 - 2.C^2_1 + 3.C^2_3 - 4.C^2_0 + 5.C^2_4 - .... + 101.C^2_{100}$ is equal to