帮忙算一下这道题1-1/2+1/6+1/12+1/20+1/30+1/40+1/50+1/70+1/90=?
来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/07/05 20:03:44
帮忙算一下这道题1-1/2+1/6+1/12+1/20+1/30+1/40+1/50+1/70+1/90=?
![帮忙算一下这道题1-1/2+1/6+1/12+1/20+1/30+1/40+1/50+1/70+1/90=?](/uploads/image/z/7253795-11-5.jpg?t=%E5%B8%AE%E5%BF%99%E7%AE%97%E4%B8%80%E4%B8%8B%E8%BF%99%E9%81%93%E9%A2%981-1%2F2%2B1%2F6%2B1%2F12%2B1%2F20%2B1%2F30%2B1%2F40%2B1%2F50%2B1%2F70%2B1%2F90%3D%3F)
1-1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+(1/6-1/7)+(1/7-1/8)+(1/8-1/9)+(1/9-1/10)
=1-1/10
=9/10
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+(1/6-1/7)+(1/7-1/8)+(1/8-1/9)+(1/9-1/10)
=1-1/10
=9/10