(m+n)!/(m+n-2)!-n!/(n-2)!=62怎么化简成 m(m+2n-1)=62 求详解

来源:学生作业帮助网 编辑:作业帮 时间:2024/05/15 17:38:32
(m+n)!/(m+n-2)!-n!/(n-2)!=62怎么化简成 m(m+2n-1)=62 求详解

(m+n)!/(m+n-2)!-n!/(n-2)!=62怎么化简成 m(m+2n-1)=62 求详解
(m+n)!/(m+n-2)!-n!/(n-2)!=62怎么化简成 m(m+2n-1)=62 求详解

(m+n)!/(m+n-2)!-n!/(n-2)!=62怎么化简成 m(m+2n-1)=62 求详解
(m+n)!/(m+n-2)!-n!/(n-2)!
=(m+n)(m+n-1)(m+n-2)!/(m+n-2)!-n(n-1)(n-2)!/(n-2)!
=(m+n)(m+n-1)-n(n-1)
=m^2+mn-m+mn+n^2-n-n^2+n
=m^2+2mn-m
= m(m+2n-1)