用规律计算(-1*2/1)+ (-2/1*3/1)+(-3/1*4/1)+...+(-2007/1*2008/1)
问题描述：
用规律计算(-1*2/1)+ (-2/1*3/1)+(-3/1*4/1)+...+(-2007/1*2008/1)
答
(-1*2/1)+ (-2/1*3/1)+(-3/1*4/1)+...+(-2007/1*2008/1)=(1/2-1)+(1/3-1/2)+(1/4-1/3)+……+(1/2008-1/2007)=1/2-1+1/3-1/2+1/4-1/3+……+1/2008-1/2007中间互相抵消=-1+1/2008=-2007/2008