19.已知函数f(x)的定义域为(-2,1),则函数f(2x-1)的定义域为( )
| A. | (-$\frac{1}{2}$,1) | B. | (-5,1) | C. | ($\frac{1}{2}$,1) | D. | (-2,1) |
16.若定义x⊕y=3x-y,则a⊕(a⊕a)等于( )
| A. | -a | B. | 3a | C. | a | D. | -3a |
15.下列函数中,满足“f(x+y)=f(x)f(y)”且在定义域内为单调递增函数的是( )
0 233638 233646 233652 233656 233662 233664 233668 233674 233676 233682 233688 233692 233694 233698 233704 233706 233712 233716 233718 233722 233724 233728 233730 233732 233733 233734 233736 233737 233738 233740 233742 233746 233748 233752 233754 233758 233764 233766 233772 233776 233778 233782 233788 233794 233796 233802 233806 233808 233814 233818 233824 233832 266669
| A. | f(x)=x${\;}^{\frac{1}{2}}$ | B. | f(x)=x3 | C. | f(x)=log2x | D. | f(x)=3x |