18.$f(x)=\left\{\begin{array}{l}{(3-a)x+1\\;x<1}\\{{a}^{x}\\;x≥1}\end{array}\right.$,满足对任意x1≠x2,都有$\frac{f({x}_{1})-f({x}_{2})}{{x}_{1}-{x}_{2}}$>0成立,那么a的取值范围是( )
| A. | (1,3) | B. | (1,2] | C. | [2,3) | D. | (1,+∞) |
17.设f(x)=2x+3x-8,则方程f(x)=0的根落在区间( )
| A. | (0,1) | B. | (1,2) | C. | (2,3) | D. | (3,4) |
16.下列函数中,既是偶数又在区间(0,+∞)上单调递减的是( )
| A. | $y=\frac{1}{x}$ | B. | y=ex | C. | y=-x2 | D. | y=lg|x| |
15.若集合U={0,1,2,3,4,5,6},M={0,1,2,3},N={1,3,5},则M∪∁UN等于( )
| A. | {0,1,2,3,4,5} | B. | {0,1,2,4,6} | C. | {0,1,2,3,4,6} | D. | {0,1,2,4,5,6} |
14.sin160°cos10°+cos20°sin10°=( )
| A. | $-\frac{{\sqrt{3}}}{2}$ | B. | $\frac{{\sqrt{3}}}{2}$ | C. | $\frac{1}{2}$ | D. | $-\frac{1}{2}$ |
12.下列各组函数f(x)与g(x)的图象相同的是( )
| A. | f(x)=x,g(x)=($\sqrt{x}$)2 | B. | $f(x)=\frac{{{x^2}-4}}{x-2}$与g(x)=x+2 | ||
| C. | f(x)=1,g(x)=x0 | D. | f(x)=|x|,g(x)=$\left\{\begin{array}{l}{x,(x≥0)}\\{-x,(x<0)}\end{array}\right.$ |
10.{an}是首顶a1=1,公差d=3的等差数列,如果an=265,则序号n等于( )
0 252426 252434 252440 252444 252450 252452 252456 252462 252464 252470 252476 252480 252482 252486 252492 252494 252500 252504 252506 252510 252512 252516 252518 252520 252521 252522 252524 252525 252526 252528 252530 252534 252536 252540 252542 252546 252552 252554 252560 252564 252566 252570 252576 252582 252584 252590 252594 252596 252602 252606 252612 252620 266669
| A. | 91 | B. | 90 | C. | 89 | D. | 88 |