15.某班为了奖励在校运会上获得好成绩的运动员,花了200元钱购买甲乙两种奖品共30件,其中甲种奖品8元/件,乙种奖品6元/件.若设购买甲种奖品x件,乙种奖品y件,则所列方程组正确的是( )
| A. | $\left\{\begin{array}{l}{8x+6y=30}\\{x+y=200}\end{array}\right.$ | B. | $\left\{\begin{array}{l}{6x+8y=30}\\{x+y=200}\end{array}\right.$ | ||
| C. | $\left\{\begin{array}{l}{x+y=30}\\{8x+6y=200}\end{array}\right.$ | D. | $\left\{\begin{array}{l}{x+y=30}\\{6x+8y=200}\end{array}\right.$ |
14.如果点P(6-2x,x-1)在第四象限,那么x的取值范围是( )
| A. | x>3 | B. | x<3 | C. | x>1 | D. | x<1 |
13.方程组$\left\{\begin{array}{l}{x+y=10}\\{2x+y=16}\end{array}\right.$的解是( )
| A. | $\left\{\begin{array}{l}{x=6}\\{y=4}\end{array}\right.$ | B. | $\left\{\begin{array}{l}{x=4}\\{y=8}\end{array}\right.$ | C. | $\left\{\begin{array}{l}{x=4}\\{y=6}\end{array}\right.$ | D. | $\left\{\begin{array}{l}{x=9}\\{y=-1}\end{array}\right.$ |
12.不等式2(1-x)>3的最大整数解是( )
| A. | 0 | B. | 1 | C. | -1 | D. | 无法确定 |
11.下列调查中,适合全面调查的是( )
0 307612 307620 307626 307630 307636 307638 307642 307648 307650 307656 307662 307666 307668 307672 307678 307680 307686 307690 307692 307696 307698 307702 307704 307706 307707 307708 307710 307711 307712 307714 307716 307720 307722 307726 307728 307732 307738 307740 307746 307750 307752 307756 307762 307768 307770 307776 307780 307782 307788 307792 307798 307806 366461
| A. | 了解旬河水中汞含量是否符合规定标准 | |
| B. | 了解县师训教研中心36名员工的健康状况 | |
| C. | 商家为了解某一批“电子白板”的使用寿命 | |
| D. | 为了解空气中PM2.5含量 |