14.已知直角三角形的两条直角边分别是3和4,则它斜边上的中线长为( )
| A. | 2.4 | B. | 2.5 | C. | 3 | D. | 5 |
13.1-(x-y)2化简后结果是( )
| A. | 1-x2+y2 | B. | 1-x2-y2 | C. | 1-x2-2xy+y2 | D. | 1-x2+2xy-y2 |
12.下列各式中属于最简二次根式的是( )
| A. | $\sqrt{{x}^{2}+1}$ | B. | x$\sqrt{\frac{y}{x}}$ | C. | $\sqrt{12}$ | D. | $\sqrt{1\frac{1}{2}}$ |
11.下列各式一定是二次根式的是( )
| A. | $\sqrt{-7}$ | B. | $\root{3}{2m}$ | C. | $\sqrt{{x}^{2}+1}$ | D. | $\sqrt{\frac{b}{a}}$ |
7.如图图形是由一些小正方形和实心圆按一定规律排列而成的,如图所示,按此规律排列下去,第20个图形中有( )个实心圆.

| A. | 38 | B. | 40 | C. | 42 | D. | 44 |
6.下列计算中,正确的是( )
| A. | $\sqrt{3}$+$\sqrt{2}$=$\sqrt{5}$ | B. | $\sqrt{12}-\sqrt{3}=\sqrt{3}$ | C. | $\sqrt{8}$÷$\sqrt{2}$=4 | D. | $\sqrt{3}$×$\sqrt{2}$=6 |
5.能判定四边形ABCD为平行四边形的题设是( )
0 288542 288550 288556 288560 288566 288568 288572 288578 288580 288586 288592 288596 288598 288602 288608 288610 288616 288620 288622 288626 288628 288632 288634 288636 288637 288638 288640 288641 288642 288644 288646 288650 288652 288656 288658 288662 288668 288670 288676 288680 288682 288686 288692 288698 288700 288706 288710 288712 288718 288722 288728 288736 366461
| A. | AB=CD,AD=BC | B. | AB∥AD,CB∥CD | C. | AB∥CD,AD=BC | D. | ∠A=∠B,∠C=∠D |