15.已知α、β为锐角,若sinα=$\frac{{2\sqrt{5}}}{5}$,sin(α+β)=$\frac{3}{5}$,则cos2β的值为( )
| A. | $-\frac{117}{125}$ | B. | $\frac{3}{5}$ | C. | $-\frac{117}{125}$或$\frac{3}{5}$ | D. | $\frac{117}{125}$ |
14.执行如图所示的程序框图,输出的结果是( )

| A. | -2 | B. | $-\frac{1}{3}$ | C. | $\frac{1}{2}$ | D. | 3 |
13.已知$\vec a$=(2,1),$\vec b$=(3,λ).若(2$\vec a-\vec b}$)∥$\vec b$,则λ的值为( )
| A. | $\frac{3}{2}$ | B. | $\frac{2}{3}$ | C. | 3 | D. | -1或3 |
12.若“?x∈[-1,m](m>-1),|x|-1>0”是假命题,则实数m的取值范围是( )
| A. | (-1,1) | B. | (-1,1] | C. | [1,+∞) | D. | [0,1] |
11.设函数f(x)=(m+nx)3=a0+a1x+a2x2+a3x3,mn≠0,则$\frac{{{a_0}{a_3}}}{{{a_1}{a_2}}}$的值为( )
| A. | $\frac{1}{9}$ | B. | $\frac{1}{6}$ | C. | $\frac{1}{3}$ | D. | 1 |
10.若不等式x2+ax+b<0的解集为(-1,2),则ab的值为( )
| A. | -1 | B. | 1 | C. | -2 | D. | 2 |
8.设变量x,y满足约束条件$\left\{\begin{array}{l}{y≤x}\\{y≥3x-6}\\{x+y≥2}\end{array}\right.$,则目标函数z=$lo{g}_{\sqrt{3}}$(2x+y)的最小值( )
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| A. | -2 | B. | -1 | C. | 1 | D. | 2 |