問題詳情
21.如右圖，在地面上朝斜前方射出一支水火箭，離發射點x公尺處時的高度為y公尺。如果x與y的關係式為y＝－x2＋6x，則這支水火箭在離發射點多遠的地方落地？
(A) 3
(B) 4
(C) 6
(D) 9
參考答案
答案：C
難度：計算中-1
書單：沒有書單，新增
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