1.|1/3-1/2|+|1/4-1/3|+|1/5-1/4|+|1/6-1/5|+|1/7-1/6|+|1/8-1/7|+|1/9-1/8|+1/10-1/9|
= 1/2-1/3+1/3-1/4+.+1/9-1/10
=1/2-1/10
=2/5
2.-(6X-2)=2X-3
2-6X=2X-3
-8X=-5
X=5/8
3.A-B-C
=-(3/8)+1/4-1/4
=-(3/8)
4.因为abcd/|abcd|=1 所以ABCD>0 ,
[- |abcd|/abcd]^2009+|a|/a+|b|/b+|c|/c+|d|/d
=(-1)^2009+ -1+-1+1+1 或 =(-1)^2009+ 1+1+1+1
=-1 或 = 3
5.差一点