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:2024/07/02 18:39:33
![1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72=?](/uploads/image/z/10241207-71-7.jpg?t=1%2F2%2B1%2F6%2B1%2F12%2B1%2F20%2B1%2F30%2B1%2F42%2B1%2F56%2B1%2F72%3D%3F)
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+1/20+1/30+1/42+1/56+1/72
=1/1 ×2+1/2×3+1/3×4……+1/8×9
=(2-1)/1 ×2+(3-2)/2×3+(4-3)/3×4……+(9-8)/8×9
=1-1/2+1/2-1/3+1/3-1/4+……+1/8-1/9
=1-1/9
=8/9