1/1X2X3+1/2X3x4+…+1/48X49X50
1/1x2x3+1/2x3x4+1/3x4x5+1/4x5x6+.+1/48x49x50=
计算1\1x2x3+1\2x3x4+1\3x4x5+``````+1\48x49x50注:(\)为分数线(x)为乘号
1/2x3x4+1/3x4x5+1/4x5x6+……+1/48x49x50=
1x2X3+2x3X4+3x4X5+…+7X8X9=?
1x2x3+2x3x4+3x4x5+…+8x9x10
1/1x2x3+1/2x3x4+1/3x4x5
求和1x2x3+2x3x4+...+n(n+1)(n+2)
1x2x3+2x3x4+3x4x5+...+7x8x9=,
1x2x3+2x3x4+3x4x5+.+10x11x12
1x2x3+2x3x4+3x4x5……+10x11x12巧算 请在两天之内回答
1x2=(1/3)(1x2x3-0x1x2) 3x4=(1/3)(3x4x5-2x3x4) 问1x2x3+2x3x4+.
数学简便计算1/1x2x3+1/2x3x4+1/3x4x5……+1/20x21x22=?