爱狗的妈妈 2008-1-24 18:38
初一数学题
已知1/2+1/5+1/8+1/11+1/20+1/41+1/110+1/1640=1，则-1/2-1/5-1/8+1/11-1/20-1/41+1/110+1/1640=_____.
zhenai 2008-1-25 10:24
-1/2-1/5-1/8+1/11-1/20-1/41+1/110+1/1640
=-1/2-1/5-1/8+1/11-1/20-1/41+1/110+1/1640 + 1/2+1/5+1/8+1/11+1/20+1/41+1/110+1/1640
-1
=2(1/11+1/110+1/1640 )-1
=33/164 - 1
= - 131/164.