摘要:已知抛物线y=x2-1上一定点B和两个动点P.Q.当P在抛物线上运动时. BP⊥PQ.则Q点的横坐标的取值范围是 . 解析:设P(t,t2-1).Q(s,s2-1)∵BP⊥PQ,∴=-1,即t2+(s-1)t-s+1=0∵t∈R,∴必须有Δ=(s-1)2+4(s-1)≥0.即s2+2s-3≥0,解得s≤-3或s≥1.
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