1/2+1/6+1/12+1/20+1/30+1/42+1/56
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/14 18:40:55
![1/2+1/6+1/12+1/20+1/30+1/42+1/56](/uploads/image/z/2508415-7-5.jpg?t=1%2F2%2B1%2F6%2B1%2F12%2B1%2F20%2B1%2F30%2B1%2F42%2B1%2F56)
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1/2+1/6+1/12+1/20+1/30+1/42+1/56
1/2+1/6+1/12+1/20+1/30+1/42+1/56
1/2+1/6+1/12+1/20+1/30+1/42+1/56
1/2+1/6+1/12+1/20+1/30+1/42+1/56
=1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+1/7*8
=(1-1/2)+(1/2-1/3)+...+(1/7-1/8)
=1-1/8
=7/8