初一数学,,今日须,,

(1)你发现的规律:_______(用含N的式子表示ING,)
-1/n×1/(n+1)=-1/n+1/(n+1)

(2)用规律计算:(需要过程)

(-1x1/2)+(-1/2x1/3)+(-1/3x1/4)+...+(-1/2007x1/2008)
=-1+1/2-1/2+1/3-1/3+1/4-1/4+......-1/2007+1/2008 (中间都正负抵消掉)
=-1+1/2008
=-2007/2008

(1)发现的规律:-(1/N)*1/(N+1)=-(1/N)+1/(N+1)

(2)(-1x1/2)+(-1/2x1/3)+(-1/3x1/4)+...+(-1/2007x1/2008)
=(-1)+1/2+(-1/2)+1/3+(-1/3)+1/4+...+(-1/2007)+1/2008
可以发现 有的可以互相抵消
=(-1)+1/2008
=-2007/2008

成功!!!!!!!!!!!!!!!!!
加油!!!!!!!!!!!!!!!!!

(1)-1/n *1/(n+1)=-1/n + 1/(n+1)

(2)原式=-1+1/2-1/2+1/3-1/3+1/4 ……-1/2007+1/2008
=-1+1/2008
=-2007/2008