12.
如图,将周长为8的△ABC沿BC方向平移n个单位得到△DEF,得四边形ABFD的周长为10,则n=( )
| A. | 2.5 | B. | 2 | C. | 1 | D. | 0.5 |
7.方程组$\left\{\begin{array}{l}{x-1=0}\\{x+1=y}\end{array}\right.$的解是( )
| A. | $\left\{\begin{array}{l}{x=1}\\{y=2}\end{array}\right.$ | B. | $\left\{\begin{array}{l}{x=1}\\{y=-2}\end{array}\right.$ | C. | $\left\{\begin{array}{l}{x=2}\\{y=1}\end{array}\right.$ | D. | $\left\{\begin{array}{l}{x=0}\\{y=-1}\end{array}\right.$ |
6.已知正比例函数y=kx的图象与反比例函数y=$\frac{m}{x}$的图象交于A,B两点,若点A的坐标为(-2,1),则关于x的方程$\frac{m}{x}$=kx的两个实数根分别为( )
| A. | x1=-1,x2=1 | B. | x1=-1,x2=2 | C. | x1=-2,x2=1 | D. | x1=-2,x2=2 |
5.关于x的一元二次方程x2-2x+k=0有两个实数根,则实数k的取值范围是( )
| A. | k≤1 | B. | k>1 | C. | k=1 | D. | k≥1 |
4.
如图,正方形ABCD的两条对角线AC,BD相交于点O,点E在BD上,且BE=CD,则∠BEC的度数为( )
0 284716 284724 284730 284734 284740 284742 284746 284752 284754 284760 284766 284770 284772 284776 284782 284784 284790 284794 284796 284800 284802 284806 284808 284810 284811 284812 284814 284815 284816 284818 284820 284824 284826 284830 284832 284836 284842 284844 284850 284854 284856 284860 284866 284872 284874 284880 284884 284886 284892 284896 284902 284910 366461
| A. | 22.5° | B. | 60° | C. | 67.5° | D. | 75° |