17.下列式子中,能分解因式的是( )
| A. | a2+b2 | B. | -a2-b2 | C. | a2-c2-2ac | D. | -4a2+b2 |
16.若分式$\frac{x-1}{x+2}$的值为0,则x的值是( )
| A. | -2 | B. | -1 | C. | 1 | D. | 0 |
15.计算3xy$÷\frac{2{y}^{2}}{3x}$的结果为( )
| A. | 2y2 | B. | $\frac{9{x}^{2}}{2y}$ | C. | $\frac{2y}{9{x}^{2}}$ | D. | 2x2y3 |
11.
如图,将等边△ABC折叠,使得点C落在AB边上的点D处,若∠ADE=90°,AD=2,则AC的长为( )
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| A. | 4 | B. | 8 | C. | 4$\sqrt{3}$ | D. | 4+2$\sqrt{3}$ |