1x2x3+2x3x4+3x4x5……+10x11x12巧算 请在两天之内回答
1x2x3+2x3x4+3x4x5……+10x11x12巧算 请在两天之内回答
1x2x3+2x3x4+3x4x5+.+10x11x12
1x2X3+2x3X4+3x4X5+…+7X8X9=?
1x2x3+2x3x4+3x4x5+…+8x9x10
(1/2x3x4)+(1/3x4x5)+.+(1/10x11x12)
1/1x2x3+1/2x3x4+1/3x4x5
1x2x3+2x3x4+3x4x5+...+7x8x9=,
请1/1x2x3+1/2x3x4+1/3x4x5+1/4x5x6=
数学简便计算1/1x2x3+1/2x3x4+1/3x4x5……+1/20x21x22=?
1/1x2x3+1/2x3x4+1/3x4x5+1/4x5x6+.+1/48x49x50=
1/1x2x3+1/2x3x4+1/3x4x5+.+1/11x12x13=
1/1x2x3+1/2x3x4+1/3x4x5+.+1/9x10x11=