=（1-1/2）+（1/2-1/3）+（1/3-1/4）+（1/4-1/5）+（1/5-1/6）+（1/6-1/7）
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7
=1-1/7
=6/7
=1/2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7
=1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7
=1/2-1/7
=(7-2)/14
=5/14本回答被网友采纳
1\/2加1\/6加1\/12加1\/20加1\/30加1\/42简便运算
1\/2+1\/6+1\/12+1\/20+1\/30+1\/42 =（1-1\/2）+（1\/2-1\/3）+（1\/3-1\/4）+（1\/4-1\/5）+（1\/5-1\/6）+（1\/6-1\/7）=1-1\/2+1\/2-1\/3+1\/3-1\/4+1\/4-1\/5+1\/5-1\/6+1\/6-1\/7 =1-1\/7 =6\/7
1\/2加1\/6加1\/12加1\/20加1\/30加1\/42简便运算
1\/2+1\/6+1\/12+1\/20+1\/30+1\/42 =（1-1\/2）+（1\/2-1\/3）+（1\/3-1\/4）+（1\/4-1\/5）+（1\/5-1\/6）+（1\/6-1\/7）=1-1\/2+1\/2-1\/3+1\/3-1\/4+1\/4-1\/5+1\/5-1\/6+1\/6-1\/7 =1-1\/7 =6\/7
简便计算1\/2+1\/6+1\/12+1\/20+1\/30+1\/42?
将分母6、12、20、30、42分解为2×3、3×4、4×5、5×6、6×7，然后再化简。1\/2+1\/6+1\/12+1\/20+1\/30+1\/42 =1\/2+1\/（2×3）+1\/（3×4）+1\/（5×6）+1\/（6×7）=1\/2+（1\/2-1\/3）+（1\/3-1\/4）+（1\/5-1\/6）+（1\/6-1\/7）=1\/2+1\/2-1\/7 =1-1\/7 ...
1\/2+1\/6+1\/12+1\/20+1\/30+1\/42的简便运算?
【为通分重新组合】=(1\/2+1\/6+1\/12)+(1\/20+1\/30)+1\/42 =(6+2+1)\/12 +(3+2)\/60 +1\/42 =9\/12 +5\/60 +1\/42 【分数约分】=(9\/12 +1\/12) +1\/42 =10\/12 +1\/42 【约分】=5\/6 +1\/42 【通分】=35\/42 +1\/42 =36\/42 【约分】=6\/7 ...
1\/2+1\/6+1\/12+1\/20+1\/30+1\/42的简便运算?
解题思路:常规思路，先通分，再求和。通分要找规律，分母方便通分的，放在一起进行计算。显然，1\/2，1\/6，1\/12这三个数分母通分都为12。1\/20，1\/30分母通分为60。所以，简便运算先算前三个数和最后一个数。原=1\/2+1\/6+1\/12+1\/42+1\/20+1\/30 =6\/12+2\/12+1\/12+1\/42+3\/60+2\/60...
1\/2+1\/6+1\/12+1\/20+1\/30+1\/42的简便运算。
1\/2+1\/6+1\/12+1\/20+1\/30+1\/42 =1\/(1x2)+1\/(2x3)+1\/(3x4)+1\/(4x5)+1\/(5x6)+1\/(6x7)=(1 -1\/2) +(1\/2-1\/3)+...+(1\/6-1\/7)=1 -1\/7 =6\/7 异分母分数相加：1、异分母分数相加，先通分，再按同分母分数相加法去计算，最后要化成最简分数。例1：3\/4+5\/7...
求1\/2+1\/6+1\/12+1\/20+1\/30+1\/42的和(用简便方法计算)
1\/2+1\/6+1\/12+1\/20+1\/30+1\/42 =1\/2+1\/2-1\/3+1\/3-1\/4+1\/4-1\/5+1\/5-1\/6+1\/6+1\/7 =8\/7
1\/2+1\/6+1\/12+1\/20+1\/30×1\/42 简便计算
1\/2+1\/6+1\/12+1\/20+1\/30+1\/42 =1-1\/2+1\/2-1\/3+1\/3-1\/4+1\/4-1\/5+1\/5-1\/6+1\/6-1\/7 =1-1\/7=6\/7 若按你的：1\/2+1\/6+1\/12+1\/20+1\/30*1\/42 =1-1\/2+1\/2-1\/3+1\/3-1\/4+1\/4-1\/5+1\/30*1\/42 =1-1\/5+1\/30*1\/42 =4\/5+1\/1260 =1009\/...
怎样简便就怎样算1\/2 1\/6 1\/12 1\/20 1\/30 1\/42
裂项法：1\/2+1\/6+1\/12+1\/20+1\/30+1\/42 =1-1\/2+1\/2-1\/3+1\/3-1\/4+1\/4-1\/5+1\/5-1\/6+1\/6-1\/7 =1-1\/7 =6\/7
1\/2 1\/6 1\/12 1\/20 1\/30 1\/42怎么用简便运算
1\/2+1\/6+1\/12+1\/20+1\/30+1\/42 =（1-1\/2）+（1\/2-1\/3）+（1\/3-1\/4）+（1\/4-1\/5）+（1\/5-1\/6）+（1\/6-1\/7）=1-1\/2+1\/2-1\/3+1\/3-1\/4+1\/4-1\/5+1\/5-1\/6+1\/6-1\/7 =1-（1\/2-1\/2）-（1\/3-1\/3）-（1\/4-1\/4）-（1\/5-1\/5）-（1\/6-1...
