Question

有关阶乘的数学题求助

有关阶乘的数学题求助如图，我试着将阶乘化简掉以后感觉运算很复杂，有没有简单方法

Answer 1

(2n+2)!=(2n+2)(2n+1)(2n)!
(n+2)!=(n+2)(n+1)(n)!
所以原式=(2n+2)(2n+1)/(n+2)(n+1)
=2(2n+1)/(n+2)
=(4n+2)/(n+2)
=10/3
3(4n+2)=10(n+2)
12n+6=10n+20
2n=14
n=7
选D

追问

多谢解答