F.1方程問題(英文)

👨🏻‍🏫 學術台數學

2009-11-24 5:48 am

1.There are 3 consecutive numbers.The sum of the smallest and the largest
numbers is 2/3 of the middle one. Find the middle number.

更新1:

趕住交功課!!!十萬火急呀

更新2:

s0rry-.- 係雙數

回答 (4)

用戶7639

2009-11-24 5:59 am

✔ 最佳答案

the middle number=0

2009-11-23 21:59:25 補充：
Let the 3 consecutive numbers be x,x+1and x+2.
x+(x+2)=2/3 (x+1)
2x+2=2/3x +2/3
4/3x=-4/3
x=-1
The middle number is 0.

2009-11-23 22:55:38 補充：
3個連續雙數？?????

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tsz leung

2009-11-24 11:03 pm

3個連續數(無論雙數, 單數, 或以k遞增, i.e. x, x+k, x+2k), 首尾兩數相加必定是中間數之2倍, 不會是2/3, 是否出錯題目??

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STEVIE-G™

2009-11-24 6:25 am

0 is an even number

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sir

2009-11-24 6:21 am

Let the smallest number is a,
then the mddle one is (a + 2),
the largest one is (a + 4)

a + (a + 4) = 2/3 x (a + 2)

2a + 4 = 2(a + 2) / 3

3(2a + 4) = 2(a + 2)

6a + 12 = 2a + 4

4a = -8

a = -2

So,
the middle one = (-2) + 2 = 0

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