1/7*5+1/7*9+1/9*11+1/11*13+1/13*15

来源:学生作业帮助网 编辑:作业帮 时间:2024/04/27 13:48:32
1/7*5+1/7*9+1/9*11+1/11*13+1/13*15

1/7*5+1/7*9+1/9*11+1/11*13+1/13*15
1/7*5+1/7*9+1/9*11+1/11*13+1/13*15

1/7*5+1/7*9+1/9*11+1/11*13+1/13*15
(1/5+1/7+1/9+1/11)*(1/7+1/9+1/11+1/13)-(1/5+1/7+1/9+1/11+1/13)*(1/7+1/9+1/11)=[(1/5)*(1/7+1/9+1/11+1/13)+(1/7+1/9+1/11)*(1/7+1/9+1/11+1/13)]-[(1/5))*(1/7+1/9+1/11)+(1/7+1/9+1/11+1/13)*(1/7+1/9+1/11)]=(1/5)*(1/7+1/9+1/11+1/13)-(1/5))*(1/7+1/9+1/11)=1/5*1/13=1/65