[中學] 對數
題目 loga (4x-7) + loga (x^2+4) = 0 求 x
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我妹沒給解答，只給題目
半年沒碰數學，算到一半卡住，能幫我看看嗎
→ (4x-7)(x^2+4) = 1
→ 4x^3 - 7x^2 + 16x - 28 = 1
→ 令y = f(x) = 4x^3 - 7x^2 + 16x - 29
→ f(1.5) < 0 , f (2) > 0
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只算到這
我只知道x在1.5~2之間有解，算的出來嗎..
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※ 編輯: Cla 來自: 118.233.155.115 (06/10 03:27)
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