16.化简Sn=n+(n-1)×2+(n-2)×22+…+2×2n-2+2n-1的结果是( )
| A. | 2n+1-n | B. | 2n+1-n+2 | C. | 2n-n-2 | D. | 2n+1-n-2 |
15.设函数f(x)满足f(n+1)=f(n)+$\frac{n}{2}$(n∈N*)且f (1)=2,则f (20)为( )
| A. | 95 | B. | 97 | C. | 105 | D. | 192 |
14.若曲线C1:x2+y2-2x=0与曲线C2:x(y-mx-m)=0有三个不同的公共点,则实数m的取值范围是( )
| A. | (0,$\sqrt{3}$) | B. | (-$\sqrt{3}$,0)∪(0,$\sqrt{3}$) | C. | (0,$\frac{{\sqrt{3}}}{3}$) | D. | (-$\frac{{\sqrt{3}}}{3}$,0)∪(0,$\frac{{\sqrt{3}}}{3}$) |
12.已知等差数列{an}满足a2=3,a5=9,若数列{bn}满足b1=3,bn+1=abn,则{bn}的通项公式为bn=( )
| A. | 2n-1 | B. | 2n+1 | C. | 2n+1-1 | D. | 2n-1+2 |
11.在△ABC中,AC=6,BC=7,cosA=$\frac{1}{5}$,O是△ABC的内心,若$\overrightarrow{OP}$=x$\overrightarrow{OA}$+y$\overrightarrow{OB}$,其中x,y∈[0,1],则动点P的轨迹所覆盖图形的面积为( )
| A. | $\frac{10\sqrt{6}}{3}$ | B. | $\frac{14\sqrt{6}}{3}$ | C. | 4$\sqrt{3}$ | D. | 6$\sqrt{2}$ |
9.已知函数f(x)=4sin($\frac{π}{3}$-2x),x∈[-π,0],则f(x)的单调递减区间是( )
0 250085 250093 250099 250103 250109 250111 250115 250121 250123 250129 250135 250139 250141 250145 250151 250153 250159 250163 250165 250169 250171 250175 250177 250179 250180 250181 250183 250184 250185 250187 250189 250193 250195 250199 250201 250205 250211 250213 250219 250223 250225 250229 250235 250241 250243 250249 250253 250255 250261 250265 250271 250279 266669
| A. | [-$\frac{7}{12}$π,-$\frac{π}{12}$] | B. | [-π,$\frac{-π}{2}$] | C. | [-π.-$\frac{7π}{12}$],[-$\frac{π}{12}$,0] | D. | [-π,-$\frac{5}{12}$π],[-$\frac{π}{12}$,0] |