請問5/6, 7/9, 9/13 那個數大D?

5/6 x 117/117 = 585/702
7/9 x 78/78 = 546/702
9/13 x 54/54 = 486/702

5/6最大, 9/13最小

答案係:5/6

因為要搵L.C.M(最少公倍數)即係要1X6X9X13

1. 數值: 5/6 最大 > 7/9 稍細 > 9/13 最細

2. 計算: 通份母。

(1) 把各分母乘起來,成為一個共用的分母: 6X9X13=702

因為13是個質數,無法跟其他分母一起分解,所以全部乘起來。

(2) 把各分子也同時增大,分母倍增多少,分子也倍增多少:

5----------------5X9X13------------585
________________________________

6X9X13----------702---------------702


7----------------7X6X13-------------546
_________________________________

9X6X13----------702---------------702


9-----------------9X6X9--------------486
__________________________________

13X6X9----------702----------------702

由於通了分母,分母相等,分子便可以作出數值上的比較。

5/6
6x9x13=702
702除以6=117,117x5=585(5/6=585/702)
702除以9=78,78x7=546(7/9=546/702)
702除以13=54,54x9=486(9/13=486/702)
約簡,是5/6大D

according to my calculator
5/6 = 0.83333333...........
7/9 = 0.77777777...........
9/13 = 0.692307692..........

from the results above, you can see 5/6 is bigger than other two.

another method is calculating the LCM (最小公倍數) of 6, 9 and 13, that will be 702.
5/6 = 585/702
7/9 = 546/702
9/13 = 486/702

so 5/6 is bigger, any questions?

5/6, 7/9, 9/13

通分母之後=585/702, 546/702, 486/702

所以,應該係5/6大d

5/6 x 117/117 = 585/702
7/9 x 78/78 = 546/702
9/13 x 54/54 = 486/702

5/6最大, 9/13最小

5/6那個數大D