=(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)］
=(1/3)×［1/(1×2×3)-1/(2×3×4)+1/(2×3×4)-1/(3×4×5)+1/(3×4×5)-1/(4×5×6)+...+1/(7×8×9)-1/(8×9×10)］
=(1/3)×［1/(1×2×3)-1/(8×9×10)］
=(1/3)×［(1/6)-(1/720)］
=(1/3)×(119/720)
=119/2160本回答被提问者采纳
...\/4x5x6x7+1\/5x6x7x8+1\/6x7x8x9+1\/7x8x9x10 求简算
=(1\/3)×(119\/720)=119\/2160
...\/4x5x6x7+1\/5x6x7x8+1\/6x7x8x9+1\/7x8x9x10 求简算
=(1\/3)×(119\/720)=119\/2160
1\/1x2x3+1\/2x3x4+1\/3x4x5+1\/4x5x6+.+1\/8x9x10 等于多少?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\/3...
1\/1x2x3+1\/2x3x4+1\/3x4x5+...+1\/8x9x10 求简算
1\/1x2x3+1\/2x3x4+1\/3x4x5+...+1\/8x9x10 =1\/2 [1\/1×2-1\/2×3＋1\/2×3-1\/3×4＋1\/3×4-1\/4×5＋。。。＋1\/8×9-1\/9×10]=1\/2[1\/2-1\/90]=1\/2×44\/90 =11\/45
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\/1x2x3x4+1\/2x3x4x5+...+1\/17x18x19x20
1\/1x2x3x4=1\/1-1\/2-1\/3-1\/4,1\/2x3x4x5=1\/2x-1\/3x-1\/4x-1\/5,以此类推结果为1\/1-1\/20=19\/20
1\/1x2x3+1\/2x3x4+1\/3x4x5+...+1\/8x9x10如何计算方法
1\/(1×2×3)=(1\/2[1\/(1×2)－1\/(2×3)]1\/(2×3×4)=(1\/2)[1\/(2×3)－1\/(3×4)]1\/(3×4×5)=(1\/2)[1\/(3×4)－1\/(4×5)]……1\/(8×9×10)=(1\/2)[1\/(8×9)－1\/(9×10)]则原式=(1\/2)[1\/(1×2)－1\/(9×10)]=(1\/2)[(1\/2)－1\/(90)]...
1\/1x2x3x4+1\/2x3x4x5+...+1\/17x18x19x20
1\/1x2x3x4=1\/1-1\/2-1\/3-1\/4,1\/2x3x4x5=1\/2x-1\/3x-1\/4x-1\/5,以此类推结果为1\/1-1\/20=19\/20
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...
1x2x3x4x5x6x7x8x9x10的简便运算
没有简便运算，如果可以用电脑，那么可以用Excel中的公式：=FACT(10)
