10.设等比数列{an}的各项均为正数,公比为q,前n项和为Sn,若对?x∈N+,有$\frac{{S}_{2n}}{{S}_{n}}$<5,则q的取值范围是( )
| A. | (0,1] | B. | (1,2) | C. | [1,$\sqrt{2}$) | D. | ($\sqrt{2}$,2) |
9.正项等比数列{an}的公比为2,若a4a10=16,则a10的值是( )
| A. | 16 | B. | 32 | C. | 64 | D. | 128 |
8.已知sinx-3cosx=$\sqrt{5}$,则tanx=( )
| A. | -2或$\frac{1}{2}$ | B. | 2或-$\frac{1}{2}$ | C. | 2或$\frac{1}{2}$ | D. | -2或-$\frac{1}{2}$ |
7.已知双曲线一条渐近线的斜率为$\sqrt{3}$,焦点是(-4,0)、(4,0),则双曲线方程为( )
0 233854 233862 233868 233872 233878 233880 233884 233890 233892 233898 233904 233908 233910 233914 233920 233922 233928 233932 233934 233938 233940 233944 233946 233948 233949 233950 233952 233953 233954 233956 233958 233962 233964 233968 233970 233974 233980 233982 233988 233992 233994 233998 234004 234010 234012 234018 234022 234024 234030 234034 234040 234048 266669
| A. | $\frac{x^2}{12}-\frac{y^2}{4}=1$ | B. | $\frac{x^2}{4}-\frac{y^2}{12}=1$ | C. | $\frac{x^2}{10}-\frac{y^2}{6}=1$ | D. | $\frac{x^2}{6}-\frac{y^2}{10}=1$1 |