原式=1/2+(1/2-1/3)+(1/3-1/4)+...+(1/2006-1/2007)
=1/2+1/2+(-1/3+1/3)+(-1/4+1/4)+...+(-1/2006+1/2006)-1/2007
=1-1/2007
=2006/2007
原式=(1-1/2)+(1/2-1/3)+(1/3-1/4)+...+(1/2006-1/2007).......拆项
= 1-1/2+1/2-1/3+1/3-1/4+...+1/2006-1/2007 ...............去括号;中间项都抵消了
=1-1/2007
=2006/2007
2006/2007
规律是1/(1*2)=1/1 - 1/2=1/2后面同理上面数所加就是1-1/2007
原式=1-1/2+1/2-1/3+……+1/2006-1/2007
=1-1/2007
=2006/2007
1/1×2=1/2,1/2×3=1/6。1/2 1/6=2/3。所以,1/2006×2007=2006/2007
=2006/2007