18.已知一元二次方程x2-2x-1=0的两根分别为m、n,则m+n的值为( )
| A. | -2 | B. | -1 | C. | 1 | D. | 2 |
15.不等式3x+2<2x+3的解集在数轴上表示正确的是( )
0 284675 284683 284689 284693 284699 284701 284705 284711 284713 284719 284725 284729 284731 284735 284741 284743 284749 284753 284755 284759 284761 284765 284767 284769 284770 284771 284773 284774 284775 284777 284779 284783 284785 284789 284791 284795 284801 284803 284809 284813 284815 284819 284825 284831 284833 284839 284843 284845 284851 284855 284861 284869 366461
| A. | B. | C. | D. |