18.若方程组$\left\{\begin{array}{l}{\frac{1}{2}x<1}\\{x>a}\end{array}\right.$有2个整数解,则a的取值范围为( )
| A. | -1<a<0 | B. | -1≤a<0 | C. | -1<a≤0 | D. | -1≤a≤0 |
15.抛物线y=2x2+n与直线y=2x-1交于点(m,3).
(1)求m,n的值;
(2)求抛物线y=2x2+n的顶点坐标和对称轴;
(3)在二次函数y=2x2+n中,当x取何值时,y随x的增大而减小?
0 287528 287536 287542 287546 287552 287554 287558 287564 287566 287572 287578 287582 287584 287588 287594 287596 287602 287606 287608 287612 287614 287618 287620 287622 287623 287624 287626 287627 287628 287630 287632 287636 287638 287642 287644 287648 287654 287656 287662 287666 287668 287672 287678 287684 287686 287692 287696 287698 287704 287708 287714 287722 366461
(1)求m,n的值;
(2)求抛物线y=2x2+n的顶点坐标和对称轴;
(3)在二次函数y=2x2+n中,当x取何值时,y随x的增大而减小?