计算题(39*2/7+2/7*4)÷2/7 7/12-(1/4-5/12) 5-3/2*10/21-2/7

问题描述:

计算题(39*2/7+2/7*4)÷2/7 7/12-(1/4-5/12) 5-3/2*10/21-2/7

(39*2/7+2/7*4)÷2/7
=(39*2/7+2/7*4)×7/2
=39+4
=43

7/12-(1/4-5/12)
=7/12-1/4+5/12
=(7/12+5/12)-1/4
=1-1/4
=3/4

5-3/2*10/21-2/7
=5-5/7-2/7
=5-(5/7+2/7)
=5-1
=4

29/84

  个人认为是先 上下乘以7,简化问题:
(39*2/7+2/7*4)÷2/7
  =(39*2+2*4)÷2
 
然后分子消去公因子2 
=39+4 = 43

还有两个差不多做法。
不知楼主是否中意这个答案,要不就选为满意答案吧。我正在完成百度知道的任务。
  

(39*2/7+2/7*4)÷2/7
=39+4
=43
7/12-(1/4-5/12)
=7/12+5/12-1/4
=1-1/4
=3/4
5-3/2*10/21-2/7
=5-(5/7+2/7)
=5-1
=4

  (39*2/7+2/7*4)÷2/7
  =(39*2/7+2/7*4)*7/2
  =39*2/7*7/2+2/7*4*7/2
  =39+4
  =43
  7/12-(1/4-5/12)
  =7/12-1/4+5/12
  =(7/12+5/12)-1/4
  =1-1/4
  3/4
  5-3/2*10/21-2/7
  =5-5/7-2/7
  =5-(5/7+2/7)
  =5-1
  =4