Question

cuanto es :
1 . 3 . 5 . 7 . ...... (2n-1)

Answer 1

$\displaystyle\,E=1\cdot3\cdot5\cdot7\cdots (2n-1)\\\\E= \dfrac{1\cdot2\cdot3\cdot4\cdots(2n-1)}{2\cdot4\cdot6\cdot8\cdots(2n-2)}\\ \\ \\E=\dfrac{\prod^{2n-1}_{i=1}i}{\prod_{j=1}^{n-1}(2j)}\,,\, n\geq 2\\ \\ \\E=\dfrac{(2n-1)!}{2^{n-1}\cdot (n-1)!}$