6.正六边形的每个内角为( )
| A. | 120° | B. | 135° | C. | 140° | D. | 144° |
5.下列四个数中,绝对值最小的数是( )
| A. | 2 | B. | -2 | C. | 0 | D. | -$\frac{1}{2}$ |
4.已知直线y=(m-3)x-3m+1不经过第一象限,则m的取值范围是( )
| A. | m≥$\frac{1}{3}$ | B. | m≤$\frac{1}{3}$ | C. | $\frac{1}{3}$≤m<3 | D. | $\frac{1}{3}$≤m≤3 |
3.函数y=$\frac{1}{x+4}$中,自变量x的取值范围是( )
| A. | x>4 | B. | x≥2 | C. | x≥2且x≠-4 | D. | x≠-4 |
2.若方程x2-2x+m=0没有实数根,则实数m为( )
| A. | m≤1 | B. | m<1 | C. | m>1 | D. | m≥1 |
1.某校运动员分组训练,若每组7人,余3人;若每组8人,则缺5人;设运动员人数为x人,组数为y组,则列方程组为( )
| A. | $\left\{{\begin{array}{l}{7y=x+3}\\{8y+5=x}\end{array}}\right.$ | B. | $\left\{{\begin{array}{l}{7y=x-3}\\{8y+5=x}\end{array}}\right.$ | C. | $\left\{{\begin{array}{l}{7y=x+3}\\{8y=x+5}\end{array}}\right.$ | D. | $\left\{{\begin{array}{l}{7y=x-3}\\{8y=x+5}\end{array}}\right.$ |
20.已知关于x的方程x2+3x+a=0有一个根为-2,则另一个根为( )
| A. | 5 | B. | 2 | C. | -1 | D. | -5 |
19.单项式xmy3与4x2yn的和是单项式,则nm的值是( )
| A. | 3 | B. | 6 | C. | 8 | D. | 9 |
18.2016年三天端午假期,天津市共迎接中外游客约1 660 000人次,将1 660000用科学记数法表示应为( )
| A. | 0.166×107 | B. | 1.66×106 | C. | 16.6×105 | D. | 166×104 |
17.将57000000用科学记数法表示应为( )
0 294564 294572 294578 294582 294588 294590 294594 294600 294602 294608 294614 294618 294620 294624 294630 294632 294638 294642 294644 294648 294650 294654 294656 294658 294659 294660 294662 294663 294664 294666 294668 294672 294674 294678 294680 294684 294690 294692 294698 294702 294704 294708 294714 294720 294722 294728 294732 294734 294740 294744 294750 294758 366461
| A. | 570×105 | B. | 57×106 | C. | 5.7×107 | D. | 0.57×108 |