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標題: [求助] 有冇人識做呢條數學題？ [打印本頁]

作者: rgdgdfh 時間: 2015-8-22 05:22 PM 標題: 有冇人識做呢條數學題？

1/a:1/b:1/c = 1:2:5

Find a:b:c

作者: mc1280 時間: 2015-8-22 05:54 PM

1/a除1/b=b/a
b:a=1:2=2:4
similarly,c:b=5:2
所以a:b:c=4:2:5?

作者: phamton1984 時間: 2015-12-30 06:34 PM

1/a:1/b=1:2
a:b=2:1
1/b:1/c=2:5
b:c =5:2
         a       b       c
a:b    2:    1
b:c                5       2
__________________
a:b:c 10:    5:       2

作者: Kitman_Fung 時間: 2016-1-10 01:25 AM

u can think in this way:

1/a: 1/b : 1/c = 1 : 2 : 5
=>
1/a: 1/b : 1/c = 1/1 : 1/(1/2) : 1/(1/5)
=>
a : b : c = 1 : 1/2 : 1/5
=> (times 10)
a : b : c = 10 : 5 : 2

in which it is a quicker way to tackle with this kind of ratio question~~~~~

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