8.函数y=3x的值域是( )
| A. | (0,+∞) | B. | (1,+∞) | C. | (-∞,0)∪(0,+∞) | D. | R |
7.已知$\overrightarrow a$,$\overrightarrow b$为非零向量,且|$\overrightarrow a$+$\overrightarrow b$|=|$\overrightarrow a$|+|$\overrightarrow b$|,则一定有( )
| A. | $\overrightarrow a$=$\overrightarrow b$ | B. | $\overrightarrow a$∥$\overrightarrow b$,且$\overrightarrow a$,$\overrightarrow b$方向相同 | ||
| C. | $\overrightarrow a$=-$\overrightarrow b$ | D. | $\overrightarrow a$∥$\overrightarrow b$,且$\overrightarrow a$,$\overrightarrow b$方向相反 |
5.已知函数f(x)=$\sqrt{2}$sin(2x-$\frac{π}{6}$),当x∈[0,$\frac{π}{2}}$]时,f(x)的最大值、最小值分别为( )
| A. | $\sqrt{2}$、-$\frac{{\sqrt{2}}}{2}$ | B. | 1、-$\frac{1}{2}$ | C. | 1、-$\frac{{\sqrt{2}}}{2}$ | D. | $\sqrt{2}$、$\frac{{\sqrt{2}}}{2}$ |
2.已知等比数列{an}的公比为2,则$\frac{{a}_{4}}{{a}_{2}}$值为( )
| A. | $\frac{1}{4}$ | B. | $\frac{1}{2}$ | C. | 2 | D. | 4 |
1.已知f(x)=$\left\{\begin{array}{l}{{2}^{x}(x≤0)}\\{lo{g}_{2}x(x>0)}\end{array}\right.$,则f(4)=( )
0 229725 229733 229739 229743 229749 229751 229755 229761 229763 229769 229775 229779 229781 229785 229791 229793 229799 229803 229805 229809 229811 229815 229817 229819 229820 229821 229823 229824 229825 229827 229829 229833 229835 229839 229841 229845 229851 229853 229859 229863 229865 229869 229875 229881 229883 229889 229893 229895 229901 229905 229911 229919 266669
| A. | 1 | B. | 2 | C. | 3 | D. | 4 |