1/1*2+1/2*3+1/3*4+……+1/2007*2008
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+……+(1/2006-2007)+(1/2007-1/2008)
脱括号互相抵消后
=1-1/2008
=2007/2008
1/1*2+1/2*3+1/3*4+……+1/2007*2008
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+……+(1/2006-2007)+(1/2007-1/2008)
脱括号互相抵消后
=1-1/2008
=2007/2008