12.下列各式中,同学们的计算结果不正确的是( )
| A. | $\sqrt{5}×\sqrt{7}$=2$\sqrt{3}$ | B. | $\sqrt{6}÷\sqrt{3}$=$\sqrt{2}$ | C. | $\sqrt{\frac{1}{10}}$×$\sqrt{8}$=$\frac{2\sqrt{5}}{5}$ | D. | $\sqrt{\frac{4}{7}}$÷$\sqrt{\frac{7}{4}}$=$\frac{4}{7}$ |
11.下列二次根式中,属于最简二次根式的是( )
| A. | $\sqrt{15}$ | B. | $\sqrt{28}$ | C. | $\sqrt{\frac{1}{6}}$ | D. | $\sqrt{0.5}$ |
10.下列式子中,不属于代数式的是( )
| A. | a+3 | B. | mn2 | C. | $\sqrt{6}$ | D. | x>y |
9.化简$\sqrt{{(-2)}^{4}}$的结果为( )
| A. | 4 | B. | 16 | C. | 2 | D. | -2 |
8.下列x的取值中,可以使$\sqrt{8-x}$有意义的是( )
0 284952 284960 284966 284970 284976 284978 284982 284988 284990 284996 285002 285006 285008 285012 285018 285020 285026 285030 285032 285036 285038 285042 285044 285046 285047 285048 285050 285051 285052 285054 285056 285060 285062 285066 285068 285072 285078 285080 285086 285090 285092 285096 285102 285108 285110 285116 285120 285122 285128 285132 285138 285146 366461
| A. | 15 | B. | 10 | C. | 9 | D. | 0 |