1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/05 20:00:54
![1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72](/uploads/image/z/37402-34-2.jpg?t=1%2F2%2B1%2F6%2B1%2F12%2B1%2F20%2B1%2F30%2B1%2F42%2B1%2F56%2B1%2F72)
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72
=(1-1/2)+(1/2-1/3)+……+(1/7-1/8)+(1/8-1/9) (中间相互抵消)
=1-1/9
=8/9
不懂问我.