15.已知向量$\vec a$,$\vec b$满足$|{\vec a}|=2\sqrt{2}|{\vec b}|≠0$,且关于x的函数$f(x)=2{x^3}+3|{\vec a}|{x^2}+6\vec a•\vec bx+7$在实数集R上单调递增,则向量$\vec a$,$\vec b$的夹角的取值范围是( )
| A. | $[{0,\left.{\frac{π}{6}}]}\right.$ | B. | $[{0,\left.{\frac{π}{3}}]}\right.$ | C. | $[{0,\left.{\frac{π}{4}}]}\right.$ | D. | $[{\frac{π}{6},\left.{\frac{π}{4}}]}\right.$ |
14.对于函数y=g(x),部分x与y的对应关系如下表:
数列{xn}满足:x1=2,且对于任意n∈N*,点(xn,xn+1)都在函数y=g(x)的图象上,则x1+x2+…+x2015=( )
| x | 1 | 2 | 3 | 4 | 5 | 6 |
| y | 2 | 4 | 7 | 5 | 1 | 8 |
| A. | 4054 | B. | 5046 | C. | 5075 | D. | 6047 |
12.已知定义域为R的函数f(x)不是偶函数,则下列命题一定为真命题的是( )
| A. | ?x∈R,f(-x)≠f(x) | B. | ?x∈R,f(-x)≠-f(x) | C. | ?x0∈R,f(-x0)≠f(x0) | D. | ?x0∈R,f(-x0)≠-f(x0) |
11.已知$\overrightarrow{a}=(1,x)$和$\overrightarrow{b}=(x+2,-2)$,若$\overrightarrow{a}⊥\overrightarrow{b}$,则|$\overrightarrow{a}+\overrightarrow{b}$|=( )
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| A. | 5 | B. | 8 | C. | $\sqrt{10}$ | D. | 64 |