12.斜率为k的直线l过抛物线C:y2=4x的焦点F,且交抛物线C于A、B两点,已知点P(-1,k),且△PAB的面积为6$\sqrt{3}$,则k的值为( )
| A. | ±$\frac{\sqrt{2}}{2}$ | B. | $\frac{\sqrt{2}}{2}$ | C. | ±$\frac{1}{2}$ | D. | $\frac{1}{2}$ |
9.已知F是抛物线y2=2x的焦点,A,B是抛物线上的两点,|AF|+|BF|=3,若直线AB的斜率为3,则线段AB的中点P的坐标为( )
0 229639 229647 229653 229657 229663 229665 229669 229675 229677 229683 229689 229693 229695 229699 229705 229707 229713 229717 229719 229723 229725 229729 229731 229733 229734 229735 229737 229738 229739 229741 229743 229747 229749 229753 229755 229759 229765 229767 229773 229777 229779 229783 229789 229795 229797 229803 229807 229809 229815 229819 229825 229833 266669
| A. | (1,$\frac{2}{3}$) | B. | (1,$\frac{1}{3}$) | C. | ($\frac{1}{3}$,1) | D. | ($\frac{2}{3}$,1) |