=1/2×(1/1×2-1/5×6)
=7/30本回答被提问者采纳
请1\/1x2x3+1\/2x3x4+1\/3x4x5+1\/4x5x6=
=1\/2×(1\/1×2-1\/2×3+1\/2×3-1\/3×4+1\/3×4-1\/4×5+1\/4×5-1\/5×6)=1\/2×(1\/1×2-1\/5×6)=7\/30
1\/1x2x3+1\/2x3x4+1\/3x4x5+1\/4x5x6+.+1\/48x49x50= 列梯等式 谢谢 急
1\/1x2x3+1\/2x3x4+1\/3x4x5+1\/4x5x6+.+1\/48x49x50=48*51÷(4*49*50)=306\/1225
1\/1x2x3+1\/2x3x4+1\/3x4x5+1\/4x5x6+...+1\/8x9x10 等于多少?急急急!!!
1\/1x2x3+1\/2x3x4+1\/3x4x5+1\/4x5x6+...+1\/8x9x10 =1-1\/2-1\/2(1-1\/3)+1\/2-1\/3-1\/2(1\/2-1\/4)+1\/3-1\/4-1\/2(1\/3-1\/5)+1\/4-1\/5-1\/2(1\/4-1\/6)+...+1\/8-1\/9-1\/2(1\/8-1\/10)=1-1\/9-1\/2(1+1\/2-1\/9-1\/10)=173\/360 ...
1\/1×2×3+1\/2×3×4+1\/3×4×5+1\/4×5×6+1\/5×6×7=的解题技巧?
1\/((n-1)*n*(n+1))=0.5*(1\/(n-1)*n-1\/n*(n+1))=0.5*[(1\/(n-1)-1\/n)-(1\/n-1\/(n+1))]=0.5*(1\/(n-1)+1\/(n+1)-2\/n) 也就是说1乘2乘3的分之一就是1加上3分之一减去2分之2，再乘以0.5后得到结果6分之一 记住这个公式哦 高三毕业都要用的哈...
1\/1x2x3x4+1\/2x3x4x5+1\/3x4x5x6+1\/4x5x6x7+1\/5x6x7x8+1\/6x7x8x9+1\/...
1\/(1×2×3×4)+1\/(2×3×4×5)+1\/(3×4×5×6)+...+1\/(7×8×9×10)=(1\/3)×［1\/(1×2×3)-1\/(2×3×4)］+(1\/3)×［1\/(2×3×4)-1\/(3×4×5)］+(1\/3)×［1\/(3×4×5)-1\/(4×5×6)］+...+(1\/3)×［1\/(7×8×9)-1\/(8×9×10)］=(...
1\/1x2x3+1\/2x3x4+1\/3x4x5+...+1\/n(n+1)(n+2)
5)+...+1\/n(1\/n+1*1\/n+2) = 1\/2-1\/1*2*3-1\/2*3*4-1\/3*4*5-...-1\/n*(n-1)*(n+1)-1\/n*1\/(n+2)将后一个式子与原式相加 得值为 1\/2 - 1\/n*1\/(n+2)n 无限大 1\/n*(n+2) 趋于零 则原问题极限值为 1\/4 望采纳 采纳 ...
1\/1x2+1\/2x3+1\/3x4+1\/4x5+1\/5x6+1\/6x7 怎样简便运算???、
1\/1x2+1\/3x2+1\/3x4+1\/4x5+1\/5x6+1\/6x7+1\/7x8=(1-1\/2)+(1\/2-1\/3)+(1\/3-1\/4)+(1\/4-1\/5)+(1\/5-1\/6)+(1\/6-1\/7)+(1\/7-1\/8)=1-1\/8 (上式前括后一项与后括号前一项抵消)=7\/8
1\/1X2+1\/2X3+1\/3X4+1\/4X5+1\/5X6+1\/6X7 用什么简便方法计算?
1\/1X2+1\/2X3+1\/3X4+1\/4X5+1\/5X6+1\/6X7 =1-1\/2+1\/2-1\/3+1\/3-1\/4+...+1\/6-1\/7 =1-1\/7 =6\/7;有帮助请记得好评，新问题请重新发帖提问，谢谢
1\/1x2+1\/2x3+1\/3x4+1\/4x5+1\/5x6+1\/6x7=?
原式=1-1\/2+1\/2-1\/3+…+1\/6-1\/7=1-1\/7=6\/7
数学简便计算
1\/1x2x3=(1\/2x1-1\/3x2)x1\/2 同理1\/n(n+1)(n+2)=(1\/(n+1)n-1\/(n+1)(n+2))x1\/2 原式可化简得 (1\/1x2-1\/2x3+...-1\/21x22)x1\/2=115\/462
