(-1*1⼀2)+(-1⼀2*1⼀3)+(-1⼀3*1⼀4)+…+(-1⼀2012*1⼀2013)

急,要快~
2025-01-02 12:16:14
推荐回答(1个)
回答1:

(-1*1/2)+(-1/2*1/3)+(-1/3*1/4)+…+(-1/2012*1/2013)
=-[(1*1/2)+(1/2*1/3)+(1/3*1/4)+…+(1/2012*1/2013)]
=-[(1-1/2)+(1/2-1/3)+(1/3-1/4)+…+(1/2012-1/2013)]
=-[1-1/2+1/2-1/3+1/3-1/4+…+1/2012-1/2013]
=-(1-1/2013)
=-2012/2013