Re: [中學] 指對數
: 要求其範圍，手邊也沒有答案，
: 還請版上高手指導
試試看：
a = 2^x >0
b = 3^y >0
c = 5^z >0
┌a + b + c = 7 => c < 7
└a/2 + b + 5c = 11 => c < 11/5
＝> b + 9c = 15 => b = 15 - 9c >0 => c < 5/3
a + (15 - 9c) + c = 7 => a = 8c - 8 >0 => c > 1
=> 1 < c < 5/3
K(c) = 2a + b + c/5 = 2(8c - 8) + (15 - 9c) + c/5 = 36c/5 -1
＝> 31/5 = K(1) < K(c) < K(5/3) = 11
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※ 編輯: Tiderus (123.240.91.95), 01/13/2016 23:53:05
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