1.若m>n,下列不等式不一定成立的是( )
| A. | m-2>n-2 | B. | $\frac{m}{2}$>$\frac{n}{2}$ | C. | m2>n2 | D. | 2m+1>2n+1 |
20.-27的立方根是( )
| A. | 3 | B. | -3 | C. | ±3 | D. | $\frac{1}{3}$ |
17.下列根式中,与$\sqrt{2}$是同类二次根式的是( )
0 285699 285707 285713 285717 285723 285725 285729 285735 285737 285743 285749 285753 285755 285759 285765 285767 285773 285777 285779 285783 285785 285789 285791 285793 285794 285795 285797 285798 285799 285801 285803 285807 285809 285813 285815 285819 285825 285827 285833 285837 285839 285843 285849 285855 285857 285863 285867 285869 285875 285879 285885 285893 366461
| A. | $\sqrt{24}$ | B. | $\sqrt{20}$ | C. | $\sqrt{\frac{3}{2}}$ | D. | $\sqrt{18}$ |