Question

用规律计算(-1*2/1)+ (-2/1*3/1)+(-3/1*4/1)+...+(-2007/1*2008/1)

Answer 1

(-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