13.正项等比数列{an}满足:a4+a3=a2+a1+8,则a6+a5的最小值是( )
| A. | 64 | B. | 32 | C. | 16 | D. | 8 |
12.已知等差数列{an}的前n项和为Sn,若S17=170,则a9的值为( )
| A. | 10 | B. | 20 | C. | 25 | D. | 30 |
11.已知向量$\overrightarrow a$=(1,1),$\overrightarrow b$=(1,-1),若$\overrightarrow c$=$-\frac{3}{2}\overrightarrow a$+$\frac{1}{2}\overrightarrow b$,则$\overrightarrow c$=( )
| A. | (-1,-2) | B. | (1,2) | C. | (-1,2) | D. | (1,-2) |
8.已知tanθ=2,则sin(2θ+$\frac{π}{4}}$)的值是( )
| A. | $-\frac{{7\sqrt{2}}}{10}$ | B. | $\frac{{7\sqrt{2}}}{10}$ | C. | $-\frac{{\sqrt{2}}}{10}$ | D. | $\frac{{\sqrt{2}}}{10}$ |
7.已知集合A={x|x2-x-2<0},B={x|x-1≤0},则A∩B=( )
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| A. | (-1,1] | B. | (-1,1) | C. | ∅ | D. | [-1,2] |