1/2+(1/3+2/3)+(1/4+2/4+3/4)+...+(1/2011+2/2011+...+2010/2011
1/2+(1/3+2/3)+(1/4+2/4+3/4)+...+(1/2011+2/2011+...+2010/2011
当x=2,1/2,3,1/3,4,1/4,…,2010,1/2010,2011,1/2011,时,
1/1×2+1/2×3+1/3×4+…+1/2010×2011+1/2012×2013
=3/2*1/2*4/3*2/3*5/4*3/4**2012/2011*2010/2011
=3/2*1/2*4/3*2/3*5/4*3/4**2012/2011*2010/2011 =1/2*2/3*3/2*4
1/1*2+1/2*3+1/3*4+……+1/2010*2011
1*2/1+2*3/1+3*4/1+…2010*2011/1等于?
2012-2011+2010-2009+.+4-3+2-1
(+1)+(-2)+(+3)+(-4)+...+(-2010)+(+2011)等于多少?
1-2+3-4+5-6+...2009-2010+2011
计算 (-1)+(+2)+(-3)+(+4)+(-5)+…+(-2010)+(+2011)
1-2+3-4+…+2009-2010+2011+2012