1/2+5/6-7/12+9/20-11/30+13/42-15/56

1\/2+5\/6-7\/12+9\/20-11\/30+13\/42-15\/56 (简便运算)
分析：5\/6=1\/2+1\/3 7\/12=1\/3+1\/4 9\/20=1\/4+1\/5 11\/30=1\/5+1\/6 13\/42=1\/6+1\/7 15\/56=1\/7+1\/8 1\/2+5\/6-7\/12+9\/20-11\/30+13\/42-15\/56 =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\/2+5\/6-7\/12+9\/20-11\/30+13\/42-15\/56 简便计算 快
等于 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=7\/8

1\/2+6\/5-7\/12+9\/20-11\/30+13\/42-15\/56=?
第二个份数好像错了，是不是这样：1\/2+5\/6-7\/12+9\/20-11\/30+13\/42-15\/56 =1\/2+（2+3）\/（2*3）-（3+4）\/（3*4）+（4+5）\/（4*5）-（5+6）\/（5*6）+（6+7）\/（6*7）-（7+8）\/（7*8）=1\/2+1\/2+1\/3-1\/3-1\/4+1\/4+1\/5-1\/5-1\/6+1\/6+1\/7-1\/...

小学数学计算:1+1\/2-5\/6+7\/12-9\/20+11\/30-13\/42+15\/56,求你了。_百度...
两个字仔细

1\/2-5\/6+7\/12-9\/20+11\/30-13\/42+15\/56用简便方法计算。(要有过程,最好...
5\/6=1\/2+1\/3 7\/12=1\/3+1\/4 ……15\/56=1\/7+1\/8 两两相消，结果为1\/8

1又1\/2-5\/6+7\/12-9\/20+11\/30-13\/42+15\/56=?
就依次老老实实计算呀 3\/2-5\/6=2\/3 2\/3+7\/12=5\/4 5\/4-9\/20=4\/5 4\/5+11\/30=7\/6 7\/6-13\/42=6\/7 6\/7+15\/56=9\/8 最后答数就是9\/8，只是每次计算的结果都有规律性而已，哈哈。

1 1\/2- 5\/6 +7\/12 -9\/20 +11\/30 -13\/42 +15\/56
分母能分为两个数的乘积，6=2*3，2+3=5是分子 5\/6=（1\/2+1\/3），7\/12=（1\/3+1\/4）以此类推 1\/2-(1\/2+1\/3)+（1\/3+1\/4）-(1\/4+1\/5)+……+（1\/7+1\/8）=1\/8

计算:1+1\/2_5\/6+7\/12_9\/20+11\/30_13\/42+15\/56
9\/8 解析：1+1\/2-5\/6+7\/12-9\/20+11\/30-13\/42+15\/56 =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 =9\/8

1加1\/2减5\/6加7\/12减9\/20加11\/30减13\/42加15\/56减17\/72。等于多少?_百 ...
5\/6=1\/2+1\/3,7\/12=1\/3+1\/4,同理可得后面的9\/20,11\/30,13\/42,15\/56,17\/72.所以原式=1+1\/2-(1\/2+1\/3)+1\/3+1\/4……-(1\/6+1\/7)+1\/7+1\/8-(1\/8+1\/9)=1-1\/9=8\/9

1+1\/2-5\/6+7\/12-9\/20+11\/30-13\/42+15\/56=? 求简便计算
1+1\/2-5\/6+7\/12-9\/20+11\/30-13\/42+15\/56 =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\/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 =9\/8 ...