[中學] 方程式
若a和a+2為異號的倆實數 且均為方程式 x^2 + |x| + 3k = 0 的解 求k值為多少 ?
請問我這樣算
把 x^2 + |x| + 3k = 0 分成
x^2 + x + 3k = 0 或 x^2 - x + 3k = 0
然後用根離係數
a+(a+2)=-1 或 a+(a+2) = 1
a= -3/2 或 a=-1/2
這樣算哪裡有錯??
解答用直接代入
為什麼一定要直接代入?
答案給 a= -1
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※ 編輯: mater2004 來自: 1.161.93.109 (09/11 21:47)
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