数学简便计算,我实在不会做求求你们了 我没悬赏分了

本团长来帮你
5×17/11-5/11×16
=5/11×（17-16）
=5/11
2/3+1/4-2/3+6.75
=2/3-2/3+0.25+6.75
=7
2004/2005×2006
=2004×2006/2005
=（2005-1）（2005+1）/2005
=（2005²-1）/2005
=2005-1/2005
=2004又2005分之2004
1/3+1/15+1/35+/1/63+1/99
=(1/3+1/15+1/35+/1/63+1/99)×2÷2
=(2/3+2/15+2/35+2/63+2/99)÷2
=(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11)÷2
=(1-1/11)÷2
=10/11÷2
=5/11
1.1+2.2+3.3+4.4+5.5+6.6
_____________________
2.2+4.4+6.6+8.8+11+13.2
=(1.1+2.2+3.3+4.4+5.5+6.6)/[2×(1.1+2.2+3.3+4.4+5.5+6.6)]
=1/2
=0.5