• # question_answer The value of ${{2}^{n}}\,\{1.3.5.....(2n-3)\,(2n-1)\}$ is A) $\frac{(2n)\,!}{n\,!}$ B) $\frac{(2n)\,!}{{{2}^{n}}}$ C) ${{2}^{n-i}}$ D) None of these

$1\ .\ 3\ .\ 5......(2n-1)\,{{2}^{n}}$$=\frac{1\,.\,2\,.\,3\,.\,4.\,5.\,6....(2n-1)\,(2n)\,{{2}^{n}}}{2.\,4.\,6.....2n}$ $=\frac{(2n)\,!\ {{2}^{n}}}{{{2}^{n}}(1\ .\ 2\ .\ 3......n)}=\frac{(2n)\ !}{n\ !}$.