数学简便计算题 快(1/5+1/7+1/9)+(1/7+1/9+1/11)+(1/7+1/9)*(1/5+1/7+1/9+1/11)简便计算

来源:学生作业帮助网 编辑:六六作业网 时间:2024/11/23 00:20:43
数学简便计算题快(1/5+1/7+1/9)+(1/7+1/9+1/11)+(1/7+1/9)*(1/5+1/7+1/9+1/11)简便计算数学简便计算题快(1/5+1/7+1/9)+(1/7+1/9+

数学简便计算题 快(1/5+1/7+1/9)+(1/7+1/9+1/11)+(1/7+1/9)*(1/5+1/7+1/9+1/11)简便计算
数学简便计算题 快
(1/5+1/7+1/9)+(1/7+1/9+1/11)+(1/7+1/9)*(1/5+1/7+1/9+1/11)
简便计算

数学简便计算题 快(1/5+1/7+1/9)+(1/7+1/9+1/11)+(1/7+1/9)*(1/5+1/7+1/9+1/11)简便计算
(1/5+1/7+1/9)*(1/7+1/9+1/11)-(1/7+1/9)*(1/5+1/7+1/9+1/11)
=(1/5+1/7+1/9)*(1/5+1/7+1/9+1/11)-(1/7+1/9)*(1/5+1/7+1/9+1/11)-1/5*(1/5+1/7+1/9)
=1/5*(1/5+1/7+1/9+1/11)-1/5*(1/5+1/7+1/9)
=1/5*1/11
=1/55.