1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/22 00:23:09
![1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)](/uploads/image/z/42167-47-7.jpg?t=1%2F2%2B%282%2F3%2B1%2F3%29%2B%283%2F4%2B2%2F4%2B1%2F4%29%2B%E2%80%A6%E2%80%A6%2B%2839%2F40%2B38%2F40%2B%E2%80%A6%E2%80%A62%2F40%2B1%2F40%29)
1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)
1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)
1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)
1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)
=0.5+1+1.5+2+...+20
=(0.5+20)+(1+19.5)+...+(10+10.5)
=20*20.5
=20*(20+0.5)
=400+10
=410