|1/3-1/2|+|1/4-1/3|+|1/5-1/4|+……|1/2004-1/2003|
=1/2-1/3+1/3-1/4+1/4-1/5+……+1/2003-1/2004
=1/2-1/2004
=1002/2004-1/2004
=1001/2004
|a-2|+|b-3|+|c-4|=0 三个非负数的和等于0,这三个非负数都等于0
a-2=0 , b-3=0 , c-4=0
a=2, b=3, c=4
a+2b+3c
=2+2×3+3×4
=2+6+12
=20
a、b互为相反数,则 a+b=0
x、y互为倒数,则 xy=1
|m|=1,则m=±1,m²=1
当m=1时:
m²-mxy+|a+b|÷m
=1-1×1+0÷1
=1-1+0
=0
当m=-1时:
m²-mxy+|a+b|÷m
=1-(-1)×1+0÷(-1)
=1+1+0
=2