2/1X2+2/2X3+2/3X4……+2/2008X2009等于多少

1/1x2+1/2x3+1/3x4+1/4x5+```````+1/2008x2009=? 1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+......1/2008x2009 1x2+2x3+3x4=3分2x(3x4)+3分3x(3x4)=3分3x4x5规律计算2008x2009分之1x(1x2 急求高手解答1/1x2+1/2x3+1/3x4+1/4x5+.+1/2007x2008+1/2008x2009帮忙列出每 解方程x1×2+x2×3+x3×4+…+x2009×2010＝2009 2/1X2+2/2X3+2/3X4+……+2/2007X2008等于多少（需要过程）急! 1/1x2+1/2x3+1/3x4...+1/2006x2007=等于多少啊! 1x2分之一+2x3分之一+3x4分之一+.+2010x2011分之一等于多少 已知|x1-1|+|x2-2|+|x3-3|+...+|x2009-2009|+|x2010-2010|=0,求代数式x 求线性方程组 x2-x3-x4=0 x1+x2-x3+3x4=1 x1-x2+x3+5x4=-1 x1+2x2-2x3+ 1+2x4-（x2+2x3） X1+2X2-X3+X4=1