=6+12+20+30+42+56+72+90+110
=(6+12+72)+(20+30+90+110)+(42+56)
=90+250+98
=438
②如果楼主原意这样，那么解法不同:
1/2x3+1/3x4+1/4x5+1/5x6+1/6x7+1/7x8+1/8x9+1/9x10+1/10x11
=1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+6/1-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11
=1/2-1/11
=9/22
(亲，希望能对你有所帮助，合作愉快，感谢采纳哦!^-^)
【俊狼猎英】团队为您解答
2x3\/1+3x4\/1+4x5\/1+5x6\/1+6x7\/1+7x8\/1+8x9\/1+9x10\/1+10x11\/1=_百度知 ...
解：①2x3\/1+3x4\/1+4x5\/1+5x6\/1+6x7\/1+7x8\/1+8x9\/1+9x10\/1+10x11\/1 =6+12+20+30+42+56+72+90+110 =(6+12+72)+(20+30+90+110)+(42+56)=90+250+98 =438 ②如果楼主原意这样，那么解法不同：1\/2x3+1\/3x4+1\/4x5+1\/5x6+1\/6x7+1\/7x8+1\/8x9+1\/9x10+1\/10...
2x3\/1+3x4\/1+4x5\/1+5x6\/1+6x7\/1+7x8\/1+8x9\/1+9x10\/1+10x11\/1=_百度知 ...
解:①2x3\/1+3x4\/1+4x5\/1+5x6\/1+6x7\/1+7x8\/1+8x9\/1+9x10\/1+10x11\/1 =6+12+20+30+42+56+72+90+110 =(6+12+72)+(20+30+90+110)+(42+56)=90+250+98 =438 ②如果楼主原意这样，那么解法不同:1\/2x3+1\/3x4+1\/4x5+1\/5x6+1\/6x7+1\/7x8+1\/8x9+1\/9x10+1\/10x1...
1x2\/1+2x3\/1+3x4\/1+4x5\/1+5x6\/1+6x7\/1+7x8\/1+8x9\/1+9x10\/1
1x2\/1+2x3\/1+3x4\/1+4x5\/1+5x6\/1+6x7\/1+7x8\/1+8x9\/1+9x10\/1 ＝1\/2+1\/6+1\/12+1\/20+1\/30+1\/42+1\/56+1\/72+1\/90 =(1-1\/2)+(1\/2-1\/3)+……+(1\/8-1\/9)+(1\/9-1\/10)=1-1\/10 =9\/10
...2\/1+2x3\/1+3x4\/1+4x5\/1+5x6\/1+6x7\/1+7x8\/1+8x9\/1 过程写清楚._百度...
1x1\/2+2x1\/3+3x1\/4+4x1\/5+5x1\/6+6x1\/7+7x1\/8+8x1\/9 ＝1\/2+2\/3+3\/4+4\/5+5\/6+6\/7+7\/8+8\/9 =33\/12+4\/5+6\/7+7\/8+8\/9 =22\/8+7\/8+4\/5+6\/7+8\/9 =29\/8+4\/5+6\/7+8\/9 =177\/40+6\/7+8\/9 1479\/280+8\/9 =14511\/1520 ...
简算题:1x2\/1+2x3\/1+3x4\/1+4x5\/1+5x6\/1+6x7\/1+7x8\/1+8x9\/1
是不是：1x1\/2+2x1\/3+3x1\/4+4x1\/5+5x1\/6+6x1\/7+7x1\/8+8x1\/9 ＝1\/2+2\/3+3\/4+4\/5+5\/6+6\/7+7\/8+8\/9 =33\/12+4\/5+6\/7+7\/8+8\/9 =22\/8+7\/8+4\/5+6\/7+8\/9 =29\/8+4\/5+6\/7+8\/9 =177\/40+6\/7+8\/9 1479\/280+8\/9 =14511\/1520 ...
1×2×3分之1+2×3×4分之1+3×4×5分之1+...+13×14×15分之1 简便计...
解：（4）原式=1\/3（1-1\/4）+1\/3（1\/4-1\/7）+1\/3（1\/7-1\/10）+1\/3（1\/10-1\/13）+1\/3（1\/13-1\/16）=1\/3（1-1\/4+1\/4-1\/7+1\/7-1\/10+1\/10-1\/13+1\/13-1\/16）=1\/3（1-1\/16）=1\/3*15\/16 =5\/16 ...
2乘4分之一加3乘5分之一加4乘6分之一加……9乘11分之一
2x1\/4+3x1\/5+4x1\/6+5x1\/7+6x1\/8+7x1\/9+8x1\/10+9x1\/11 =2\/4+3\/5+4\/6+5\/7+6\/8+7\/9+8\/10+9\/11 =77989\/13860 =5+8689\/13860 =5.62691197(691197循环)
...5X1\/6+5X6X1\/7+6X7X1\/8+7X8X1\/9+8X9X1\/10+9X10X1\/11求和?
因为an=n*(n-1)\/n+1 所以每个数可以看成2\/3+（1+2\/4）+（2+2\/5）+（3+2\/6）...+（8+2\/11）= 1+2+3...+8+2\/3+2\/4+2\/5...+2\/11=36+2*（1\/3+1\/4+1\/5+...1\/11）因为后面的那个是一个发散数列，好像没有求和公式，所以只能同分计算，当然可以把简单的算出来，...
...5X1\/6+5X6X1\/7+6X7X1\/8+7X8X1\/9+8X9X1\/10+9X10X1\/11求和?
因为an=n*(n-1)\/n+1 所以每个数可以看成2\/3+（1+2\/4）+（2+2\/5）+（3+2\/6）...+（8+2\/11）= 1+2+3...+8+2\/3+2\/4+2\/5...+2\/11=36+2*（1\/3+1\/4+1\/5+...1\/11）因为后面的那个是一个发散数列，好像没有求和公式，所以只能同分计算，当然可以把简单的算出来，...
1x2x3分之一+2x3x4分之一+...+8x9x10分之一+9x10x11分之一怎么简便_百...
裂项法：1x2x3分之一+2x3x4分之一+...+8x9x10分之一+9x10x11分之一 =1\/2×（1\/1x2-1\/2x3+1\/2x3-1\/3x4+...+1\/8x9-1\/9x10+1\/9x10-1\/10x11）=1\/2×（1\/1x2-1\/10x11）=1\/2×（1\/2-1\/110）=1\/2×54\/110 =27\/110 ...
