将下列分数按降序排列。
(i) $\frac{2}{9}, \frac{2}{3} \times \frac{8}{21} $
(ii) $\frac{1}{5}, \frac{3}{7}+\frac{7}{10} $
在一个幻方中"
已知
$(i)\ \frac{2}{9}, \frac{2}{3} \times \frac{8}{21}$
$(ii)\ \frac{1}{5}, \frac{3}{7}, \frac{7}{10}$
解答:
$(i)\ \frac{2}{9}, \frac{2}{3} \times \frac{8}{21}$
3、9、21的最小公倍数是63
给定的分数可以改写为
$\frac{14}{63}$, $\frac{42}{63}$, $\frac{24}{63}$
所以降序排列为 $\frac{42}{63}$, $\frac{24}{63}$, $\frac{14}{63}$
或 $\frac{2}{3}$, $\frac{8}{21}$, $\frac{2}{9}$ 或
$\frac{2}{3}> \frac{8}{21}> \frac{2}{9}$
$(ii)\ \frac{1}{5}, \frac{3}{7}, \frac{7}{10} $
5、7、10的最小公倍数是70
给定的分数可以改写为 $\frac{14}{70}$, $\frac{30}{70}$, $\frac{49}{70}$
降序排列为 $\frac{49}{70} > \frac{30}{70} > \frac{14}{70}$
或 $\frac{7}{10} > \frac{3}{7} > \frac{1}{5}$
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