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1X2X3+2X3X4+.+n(n+1)(n+2)

来源：学生作业帮 编辑：大师作文网作业帮 分类：综合作业 时间：2024/11/10 11:41:51
1X2X3+2X3X4+.+n(n+1)(n+2)
1X2X3+2X3X4+.+n(n+1)(n+2)
1*2*3+2*3*4+.+n*(n+1)(n+2)
=1/4[(1*2*3*4-0*1*2*3)+(2*3*4*5-1*2*3*4)+.+
n(n+1)(n+2)(n+3)-(n-1)n(n+1)(n+2)]
=1/4*n(n+1)(n+2)(n+3)
求和1x2x3+2x3x4+...+n(n+1)(n+2) 1x2x3+2x3x4+3x4x5+4x5x6+...+n(n+1)(n+2)= 1/(1x2x3)+1/(2x3x4)+1/(3x4x5)+.1/(nx(n+1)x(n+2)=? 急,裂项法计算1.1/1x2x3+1/2x3x4+…+1/n(n+1)(n+2）2.2/(X+2)(X+4)+2/(X+ 3.1x2x3+2+3x4+…+n(n+1)（n+2) 1/1x2x3+1/2x3x4+1/3x4x5 1x2X3+2x3X4+3x4X5+…+7X8X9=? 1x2x3+2x3x4+3x4x5+…+8x9x10 1x2x3+2x3x4+3x4x5+...+7x8x9=, 1x2x3+2x3x4+3x4x5+.+10x11x12 1x2=(1/3)(1x2x3-0x1x2) 3x4=(1/3)(3x4x5-2x3x4) 问1x2x3+2x3x4+. 2^n/n*(n+1)