12.一元二次方程x2-4x+1=0的根的情况是( )
| A. | 没有实数根 | B. | 只有一个实数根 | ||
| C. | 有两个相等的实数根 | D. | 有两个不相等的实数根 |
11.一元二次方程x2-16=0的根是( )
| A. | x=2 | B. | x=4 | C. | x1=2,x2=-2 | D. | x1=4,x2=-4 |
10.下列各式中,是最简二次根式的是( )
0 288691 288699 288705 288709 288715 288717 288721 288727 288729 288735 288741 288745 288747 288751 288757 288759 288765 288769 288771 288775 288777 288781 288783 288785 288786 288787 288789 288790 288791 288793 288795 288799 288801 288805 288807 288811 288817 288819 288825 288829 288831 288835 288841 288847 288849 288855 288859 288861 288867 288871 288877 288885 366461
| A. | $\sqrt{3}$ | B. | $\sqrt{9}$ | C. | $\sqrt{\frac{1}{4}}$ | D. | $\sqrt{0.5}$ |