简便计算1/2+1/2x3+1/3x4+1/4x5+...+1/99x100

简便计算1/2+1/2x3+1/3x4+1/4x5+...+1/99x100 计算1x2+2x3+3x4+4x5+...+99x100 1x1-2x2+3x3-4x4+5x5-6x6.-100x100+101x101 1/1x2+1/2x3+1/3x4+1/4x5+.+1/98x99+1/99x100 1/1X2+1/2x3+1/3x4+1/4x5+.+1/98x99+1/99x100求结果! 一定要帮我啊!(1/1x2)+(1/2x3)+(1/3x4)+(1/4x5)+.+(1/99x100)=? 2/1x2+2/2x3+2/3x4+2/4x5+...+2/98x99+2/99x100 求1x2,2x3,3x4,4x5,……98x99,99x100的倒数和 一道简便计算数学题1X2+2X3+3X4+4X5...+n(n+1)一1X2+2X3+3X4+4X5...+2013X2 1/1x2+1/2x3+1/3x4+1/4x5...1/2001x2002 简便计算 求齐次线性方程组x1+2x2+x3+x4+x5=1 2x1+4x2+3x3+x4+x5=2 -x1-2x2+x3+3x4 解方程组X2+X3+X4=1 X1+X2+X3=5 X3+X4+X5=-5 X4+X5+X1=-3 X5+X1+X2=2