19.已知f(x)=$\left\{\begin{array}{l}{x+3,x≤1}\\{-{x}^{2}+2x+3,x>1}\end{array}\right.$,则使得f(x)-ex-m≤0恒成立的m的取值范围是( )
| A. | (-∞,2) | B. | (-∞,2] | C. | (2,+∞) | D. | [2,+∞) |
17.不等式|2x-log2x|<2x+|log2x|成立,则( )
| A. | 1<x<2 | B. | 0<x<1 | C. | x>1 | D. | x>2 |
16.已知函数y=2sin($\frac{2}{9}$x-$\frac{20π}{27}$),把它的图象向左平移$\frac{π}{3}$个单位,再使其图象上每点的纵坐标不变,横坐标缩小为原来的$\frac{1}{3}$,得到的图象对应的解析式为( )
0 228584 228592 228598 228602 228608 228610 228614 228620 228622 228628 228634 228638 228640 228644 228650 228652 228658 228662 228664 228668 228670 228674 228676 228678 228679 228680 228682 228683 228684 228686 228688 228692 228694 228698 228700 228704 228710 228712 228718 228722 228724 228728 228734 228740 228742 228748 228752 228754 228760 228764 228770 228778 266669
| A. | y=2sin($\frac{2}{3}$x-$\frac{π}{9}$) | B. | y=2sin($\frac{2}{3}$x-$\frac{2π}{3}$) | C. | y=2sin($\frac{2}{3}$x-$\frac{5π}{9}$) | D. | y=2sin(6x-$\frac{7π}{3}$) |