1.|1/3-1/2|+|1/4-1/3|+|1/5-1/4|······+|1/10-1/9|
=1/2-1/3+1/3-1/4+1/4-1/5……+1/9-1/10=1/2-1/10=2/5
2.1/a-1/b=(b-a)/(a*b)
所以 当a>b 时b-a-b>b>-a
7.-1
8.同第一题
1.|1/3-1/2|+|1/4-1/3|+|1/5-1/4|······+|1/10-1/9|
=1/2-1/3+1/3-1/4+1/4-1/5……+1/9-1/10=1/2-1/10=2/5
2.1/a-1/b=(b-a)/(a*b)
所以 当a>b 时b-a-b>b>-a
7.-1
8.同第一题