15.要使$\frac{x-1}{x-3}$有意义,则x的取值范围是( )
| A. | x≠1 | B. | x≠3 | C. | x≥1且x≠3 | D. | x≥3且x≠1 |
13.
二次函数y=ax2+bx+c(a≠0)图象如图所示,则下列结论中错误的是( )
| A. | 当m≠1时,a+b>am2+bm | |
| B. | 若a${x}_{1}^{2}$+bx1=a${x}_{2}^{2}$+bx2,且x1≠x2,则x1+x2=2 | |
| C. | a-b+c>0 | |
| D. | abc<0 |
11.在平面直角坐标系中,下列函数的图象经过原点的是( )
| A. | y=-2x+1 | B. | y=-2x | C. | y=-$\frac{2}{x}$ | D. | y=-x2+1 |
8.计算743×369-741×370的值是( )
| A. | -3 | B. | -2 | C. | 3 | D. | 7 |
6.
如图,在正方形ABCD中,AB=2,延长AB至点E,使得BE=1,EF⊥AE,EF=AE.分别连接AF,CF,M为CF的中点,则AM的长为( )
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| A. | 2$\sqrt{2}$ | B. | 3$\sqrt{2}$ | C. | $\frac{11}{4}$ | D. | $\frac{\sqrt{26}}{2}$ |