已知动点P的轨迹为曲线C,且动点P到两个定点F 1 (-1,0),F 2 (1,0)的距离 | P F 1 |,| P F 2 | 的等差中 2 . (1)求曲线C的方程; (2)直线l过圆x 2 +y 2 +4y=0的圆心Q与曲线C交于M,N两点,且 ON ? OM =0(O 为坐标原点),求直线l的方程; (3)设点 A(1, 1 2 ) ,点P为曲线C上任意一点,求 | PA |+ 2 | P F 2 | 的最小值,并求取得最小值时点P的坐标.
【简答题】What Work Environments Do? Work environments are than as varied (31) there are types of businesses. (32) it is a large corporation with multiple departments and locations, or a small business with onl...
【单选题】Please arrange for the workers to do the ______ work during loading the trucks and heavy cargo on the ship, and also supply the necessary materials for the work.