異分母分數的減法

1. 4分之3 減 6分之1
= 3/4 - 1/6
= 9/12 - 2/12
= 7/12

2. 2又2分之1 減 7分之10
= 5/2 - 10/7
= 35/14 - 20/14
= 15/14
= 1又14分之1

3. 1又6分之1 減 12分之5
= 7/6 - 5/12
= 14/12 - 5/12
= 9/12
= 3/4

4. 4分之21 減 2又3分之1
= 21/4 - 7/3
= 63/12 - 28/12
= 35/12
= 2又12分之11

5. 7又8分之7 減 4又6分之4
= 63/8 - 28/6
= 63/8 - 14/3
= 189/24 - 112/24
= 77/24
= 3又24分之5

6. 2又9分之5 減 12分之17
= 23/9 - 17/12
= 92/36 - 51/36
= 41/36
= 1又36分之5

2013-10-18 20:12:12 補充：
致 回答者001:
第1題的答案 (2/3) 是錯的

你自己要先試做呀！
不可以就這樣子抄～

你看看：
http://imgcld.yimg.com/8/n/HA00430218/o/20131017205229.jpg

1.3/4 - 1/6 = 9/12 - 2-12 = 8/12 = 2/3
2. 2/1/2 - 10/7 = 5/2 - 10/7 = 35/14- 20/14 =15/14
3.1/1/6 - 5/12 = 7/6 -5/12 = 14/12 - 5/12 =9/12 =3/4
4.21/4 - 2/1/3 = 21/4 - 7/3 =63/12 -28/12 =35/12
5.7/7/8 - 4/4/6 = 63/8 - 28/6 = 189/24 - 112/24 = 77/24
6.2/5/9 - 17/12 = 23/9 -17/12 =92/36- 51/36 =41/36