✨ 最佳解答 ✨
垂直 x 軸 => x = 某個數字 => y 項係數 = 0
--> a = 0
L: 2x = 0, x = 0 --> y 軸
M: -x = 1, x = -1
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y = ax^2 + bx + c (1, 2)
=> a + b + c = 2
y = -1 為對稱軸 => 對稱點 (1, -4)
y = px^2 + qx + r
=> p + q + r = -4
(a + b + c) - (p + q + r) = 6
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