3.抛物线y=2x2+4x-1的顶点关于原点对称的点的坐标是( )
| A. | (-1,3) | B. | (-1,-3) | C. | (1,3) | D. | (1,-3) |
2.已知x=$\frac{1}{2}$,y-$\frac{1}{2}$的绝对值为$\frac{3}{2}$,则(5x2y+5xy-7x)-(4x2y+5xy-7x)的值为( )
0 309632 309640 309646 309650 309656 309658 309662 309668 309670 309676 309682 309686 309688 309692 309698 309700 309706 309710 309712 309716 309718 309722 309724 309726 309727 309728 309730 309731 309732 309734 309736 309740 309742 309746 309748 309752 309758 309760 309766 309770 309772 309776 309782 309788 309790 309796 309800 309802 309808 309812 309818 309826 366461
| A. | -$\frac{1}{4}$或-$\frac{1}{2}$ | B. | $\frac{1}{4}$或-$\frac{1}{2}$ | C. | -$\frac{1}{4}$或$\frac{1}{2}$ | D. | $\frac{1}{4}$或$\frac{1}{2}$ |