20.已知集合A={x|x2<1},B={y|y=|x|},则A∩B=( )
| A. | ∅ | B. | (0,1) | C. | [0,1) | D. | [0,1] |
17.已知等差数列{an}中,a8+a9=32,a7=1,则a10的值是( )
| A. | 15 | B. | 30 | C. | 31 | D. | 64 |
16.已知向量$\overrightarrow{a}$=(2,1),$\overrightarrow{b}$=(-3,4),则2$\overrightarrow{a}$-$\overrightarrow{b}$=( )
| A. | (7,-2) | B. | (6,-2) | C. | (-1,6) | D. | (-2,7) |
14.已知等比数列{an}的前n项和为Sn,且a1+a3=$\frac{5}{4}$,a2+a4=$\frac{5}{2}$,则$\frac{S_6}{S_3}$=( )
| A. | $\frac{1}{2}$ | B. | $\frac{9}{8}$ | C. | 2 | D. | 9 |
13.已知等差数列{an}中,a2=1,a3+a5=4,则该数列公差为( )
| A. | $\frac{1}{2}$ | B. | 1 | C. | $\frac{3}{2}$ | D. | 2 |
11.在△ABC中,三内角A、B、C的对边分别是a、b、c.若4a2=b2+c2+2bc,sin2A=sinB•sinC,则△ABC的形状的形状为( )
0 229726 229734 229740 229744 229750 229752 229756 229762 229764 229770 229776 229780 229782 229786 229792 229794 229800 229804 229806 229810 229812 229816 229818 229820 229821 229822 229824 229825 229826 229828 229830 229834 229836 229840 229842 229846 229852 229854 229860 229864 229866 229870 229876 229882 229884 229890 229894 229896 229902 229906 229912 229920 266669
| A. | 等边三角形 | B. | 等腰三角形 | C. | 直角三角形 | D. | 等腰直角三角形 |