13.我旗某学校组织教师34人分别到长胜和苏独仑进参加“十个全覆盖”工作,到苏独仑的人数是到长胜的人数的2倍多1人,求到两地的人数各是多少?设到苏独仑的人数为x人,到长胜的人数为y人,下列方程组正确的是( )
| A. | $\left\{\begin{array}{l}{x+y=34}\\{x+1=2y}\end{array}\right.$ | B. | $\left\{\begin{array}{l}{x+y=34}\\{x=2y+1}\end{array}\right.$ | C. | $\left\{\begin{array}{l}{x+y=34}\\{2x=y+1}\end{array}\right.$ | D. | $\left\{\begin{array}{l}{x+2y=34}\\{x=2y+1}\end{array}\right.$ |
12.下列运算,正确的是( )
| A. | 4a-2a=2 | B. | a6÷a3=a2 | C. | (a-b)2=a2-b2 | D. | (-a3b)2=a6b2 |
9.某市今年预计建成34个地下调蓄设施,蓄水能力达到140000立方米,将140000用科学记数法表示应为( )
| A. | 14×104 | B. | 1.4×105 | C. | 1.4×106 | D. | 0.14×106 |
8.下列计算正确的是( )
| A. | 3x2-4x2=-1 | B. | 3x+x=3x2 | C. | 4x•x=4x2 | D. | -4x6÷2x2=-2x3 |
7.在实数-2$\sqrt{5}$、0、-5、3中,最小的实数是( )
| A. | -2$\sqrt{5}$ | B. | 0 | C. | -5 | D. | 3 |
5.在下列各数-(+3)、-22、(-2)2、(-1)2015、-|-4|中,负数有( )个.
0 284664 284672 284678 284682 284688 284690 284694 284700 284702 284708 284714 284718 284720 284724 284730 284732 284738 284742 284744 284748 284750 284754 284756 284758 284759 284760 284762 284763 284764 284766 284768 284772 284774 284778 284780 284784 284790 284792 284798 284802 284804 284808 284814 284820 284822 284828 284832 284834 284840 284844 284850 284858 366461
| A. | 2个 | B. | 3个 | C. | 4个 | D. | 5个 |