已知动点P到定点(1,0)和定直线x=3的距离之和为4,则点P的轨迹方程为()
A: y2＝4x
B: y2＝－12(x－4)
C: y2＝4x(x≥3)或y2＝－12(x－4)(x<3)
D: y2＝4x(x≤3)或y2＝－12(x－4)(x>3)
A: y2＝4x
B: y2＝－12(x－4)
C: y2＝4x(x≥3)或y2＝－12(x－4)(x<3)
D: y2＝4x(x≤3)或y2＝－12(x－4)(x>3)
举一反三
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