1/2*1/3+1/3*1/4+1/4*1/5.+1/18*1/19+1/19*1/20

(1+1/2+1/3+1/4+1/5)*(1/3+1/4+1)-(1+1/3+1/4)*(1/2+1/3+1/4+1/5) 1+2+3+4+1 (1+1/2+1/3+1/40)*(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4)(1+1/2+1/3+1/4)*(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4),不好意思,是下面这个! /1/3-1/2/+/1/4-1/3/+/1/5-1/4/+.+/1/10-1/9/ |1/3-1/2|+|1/4-1/3|+|1/5-1/4|+.+|1/2008-1/2007| |1/3-1/2|+|1/4-1/3|+|1/5-1/4|+...+|1/10-1/9| 1/2 1/3 1/4是勾股数吗 1/3+1/2+1/4 1/2*1/3*1/4 1/2+1/3+1/4=? 1/2-3/1-4/1= 1 2 3 4 1 2 3 4 1 2 3 4 1,2,3,4, 1 2 3 4 1 2 3 4 1,2,3,4,