7.在平面直角坐标系中,把一条抛物线先向上平移3个单位长度,然后绕原点旋转180°得到抛物线y=x2+5x+6,则原抛物线的解析式是( )
| A. | y=-(x-$\frac{5}{2}$)2-$\frac{11}{4}$ | B. | y=-(x+$\frac{5}{2}$)2-$\frac{11}{4}$ | C. | y=-(x-$\frac{5}{2}$)2-$\frac{1}{4}$ | D. | y=-(x+$\frac{5}{2}$)2+$\frac{1}{4}$ |
6.抛物线y=2x2-2$\sqrt{2}$x+1与坐标轴的交点个数是( )
| A. | 0 | B. | 1 | C. | 2 | D. | 3 |
4.对于不等式组$\left\{\begin{array}{l}{\frac{1}{2}x-1≤7-\frac{3}{2}x}\\{5x+2>3(x-1)}\end{array}\right.$下列说法正确的是( )
0 283648 283656 283662 283666 283672 283674 283678 283684 283686 283692 283698 283702 283704 283708 283714 283716 283722 283726 283728 283732 283734 283738 283740 283742 283743 283744 283746 283747 283748 283750 283752 283756 283758 283762 283764 283768 283774 283776 283782 283786 283788 283792 283798 283804 283806 283812 283816 283818 283824 283828 283834 283842 366461
| A. | 此不等式组无解 | B. | 此不等式组有7个整数解 | ||
| C. | 此不等式组的负整数解是-3,-2,-1 | D. | 此不等式组的解集是-$\frac{5}{2}$<x≤2 |