Re: [其他] 腦筋急轉彎數學問題 求救
※ 引述《juiminliu (平凡就是福)》之銘言：
: 你有一束花,當中除了2朵外,都是玫瑰花;
: 除了2朵外,都是雛菊;
: 除了2朵外,都是鬱金香.
: 你一共有多少花?
: 謝謝~
設全部的花 = n
3種花以外的其他花 = k
由題意：
玫瑰 = n-2
雛菊 = n-2
鬱金香 = n-2
其中n是正整數，而且n>2，k為非負整數
(不大過2的話，玫瑰、雛菊、鬱金香的數目是負數，不合)
玫瑰 + 雛菊 +鬱金香 + 3種花以外的其他花 = 全部花
=> (n-2) + (n-2) + (n-2) + k = n
=> 3n - 6 + k = n
=> 2n = 6 - k
=> n = (6 - k)/2
=> 2 < (6 - k)/2 (n>2)
=> k < 2
所以k只可能是0或1
如果k是1:
n = (6 - 1)/2
n = 5/2
n = 2.5 (因不是整數,所以捨去)
如果k是0:
n = (6 - 0)/2
n = 6/2
n = 3 (符合條件)
所以
全部花 = n = 3
3種花以外的其他花 = k = 0
玫瑰 = n-2 = 3-2 = 1
雛菊 = n-2 = 3-2 = 1
鬱金香 = n-2 = 3-2 = 1
--
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