7.已知f(t)=log2t,t∈[2,16],对于函数f(t)值域内的任意实数m,则使x2+mx+4>4m+4x恒成立的实数x的取值范围为( )
| A. | (-∞,-2$\sqrt{3}$] | B. | [2,+∞) | C. | (-∞,-2$\sqrt{3}$]∪[2$\sqrt{3}$,+∞) | D. | (-∞,-2$\sqrt{3}$)∪(2$\sqrt{3}$,+∞) |
6.设变量x,y满足约束条件$\left\{\begin{array}{l}{x≥0}\\{x-y≥0}\\{2x-y-2≤0}\end{array}\right.$,则z=3x-2y的最大值是( )
| A. | 8 | B. | 5 | C. | 6 | D. | 4 |
5.抛物线C:y2=2px(p>0)的焦点与圆F:x2+y2-4x=0的圆心重合,点A,B,C在该抛物线上,且点F是△ABC的重心,则|FA|+|FB|+|FC|的值是( )
| A. | 6 | B. | 8 | C. | 9 | D. | 12 |
4.若等差数列{an}满足a1+a2+a2015+a2016=3,则{an}的前2016项之和S2016=( )
| A. | 1506 | B. | 1508 | C. | 1510 | D. | 1512 |
2.方程$\sqrt{{x^2}+{{(y-2)}^2}}+\sqrt{{x^2}+{{(y+2)}^2}}=10$化简的结果是( )
| A. | $\frac{x^2}{25}+\frac{y^2}{16}=1$ | B. | $\frac{x^2}{25}+\frac{y^2}{21}=1$ | C. | $\frac{x^2}{25}+\frac{y^2}{4}=1$ | D. | $\frac{y^2}{25}+\frac{x^2}{21}=1$ |
1.设变量x,y满足约束条件$\left\{\begin{array}{l}{x+y≤3}\\{x-y≥-1}\\{y≥1}\end{array}\right.$,则目标函数z=4x+2y的最大值为( )
| A. | 12 | B. | 10 | C. | 8 | D. | 2 |
18.在△ABC中,角A,B,C所对的三边分别是a,b,c,已知$A={30°},c=2\sqrt{3},b=2$,则△ABC的面积为( )
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| A. | $\sqrt{2}$ | B. | $\sqrt{3}$ | C. | $\frac{{\sqrt{3}}}{2}$ | D. | $\frac{{\sqrt{2}}}{2}$ |