8.已知关于x的方程x2+1=$\frac{k}{x}$有一个正的实数根,则k的取值范围是( )
| A. | k<0 | B. | k≤0 | C. | k>0 | D. | k≥0 |
6.把抛物线y=-x2向左平移1个单位,然后向上平移3个单位,则平移后抛物线的解析式为( )
| A. | y=-(x-1)2+3 | B. | y=-(x+1)2+3 | C. | y=-(x+1)2-3 | D. | y=-(x-1)2-3 |
5.在Rt△ABC中,∠C=90°,AC=3,BC=4,那么sinB的值是( )
| A. | $\frac{3}{4}$ | B. | $\frac{4}{3}$ | C. | $\frac{4}{5}$ | D. | $\frac{3}{5}$ |
4.据科学家估计,地球的年龄大约是4600000000年,将4600000000用科学记数法表示为( )
| A. | 4.6×108 | B. | 46×108 | C. | 4.69 | D. | 4.6×109 |
3.
如图,在△ABC中,∠B、∠C的平分线BE,CD相交于点F,∠A=60°,则∠BFC=( )
| A. | 118° | B. | 119° | C. | 120° | D. | 121° |
2.在直角坐标系中与(2,-3)在同一个正比例函数图象上的是( )
0 293774 293782 293788 293792 293798 293800 293804 293810 293812 293818 293824 293828 293830 293834 293840 293842 293848 293852 293854 293858 293860 293864 293866 293868 293869 293870 293872 293873 293874 293876 293878 293882 293884 293888 293890 293894 293900 293902 293908 293912 293914 293918 293924 293930 293932 293938 293942 293944 293950 293954 293960 293968 366461
| A. | (2,3) | B. | (-2,-3) | C. | (4,-6) | D. | (-4,-6) |