率與比(form2數學)

1. 設那三個數分別為 3k, 4k, 5k, k 是一實數
5k - 3k = 10
2k = 10
k = 5
所以, 那三個正數是 15, 20, 25.

2.
a : c = 1 : 2 = 3 : 6
a : b = 3 : 2
a : b : c = 3 : 2 : 6

3. (2x - y) : (2x + y) = 3 : 7
(2x - y) / (2x + y) = 3/7
7 (2x - y) = 3 (2x + y)
14x - 7y = 6x + 3y
8x = 10y
x/y = 10/8 = 5/4
x : y = 5 : 4

4.
a : b = 3 : 2 = 9 : 6
b : c = 3 : 4 = 6 : 8
a : b : c = 9 : 6 : 8

1. 50,40,30
2 a:c=1:2
a:c=3:6
a:b=3:2
a:b:c=3:2:6
3 (2x-y)/(2x+y)=3/7
14x-7y=6x+3y
8x=10y
x/y=5/4
x:y=5:4
4 a:b=3:2
a:b=9:6
b:c=3:4
b:c=6:8
a:b:c=9:6:8

2007-08-08 21:04:23 補充：
What is the difference of each number? Your writing is not clear, I may misunderstand your question!

2007-08-09 16:28:46 補充：
If the largest number differs the smallest number by 10,the answer will be 25,20,15