Question

1*3*5*7*...*2n-1 怎么用阶乘表示,最好有推导过程

Answer 1

1*2*3*4*5*...*2n-1=(2n-1)!(1)

2*4*6*8*...*2n=2*(1*2*3*4*...*n)=2*n!(2)

(1)/(2)=1*3*5*7*...*2n-1=(2n-1)!/2n!