1.已知A={x|x2=1},B={x|x=$\frac{1}{a}$},若B⊆A,则a的值为( )
| A. | 1或-1 | B. | 0或1或-1 | C. | -1 | D. | 1 |
20.已知a=(0.3)0.4,b=(0.6)0.4,c=log0.32,则a,b,c的大小关系是( )
| A. | a>b>c | B. | b>a>c | C. | a>c>b | D. | c>b>a |
19.下列各组函数中,表示同一函数的是( )
0 233520 233528 233534 233538 233544 233546 233550 233556 233558 233564 233570 233574 233576 233580 233586 233588 233594 233598 233600 233604 233606 233610 233612 233614 233615 233616 233618 233619 233620 233622 233624 233628 233630 233634 233636 233640 233646 233648 233654 233658 233660 233664 233670 233676 233678 233684 233688 233690 233696 233700 233706 233714 266669
| A. | $f(x)=\frac{{{x^2}+x}}{x+1}$与g(x)=x-1 | B. | f(x)=2|x|与$g(x)=\sqrt{4{x^2}}$ | ||
| C. | $f(x)=\sqrt{x^2}$与$g(x)={(\sqrt{x})^2}$ | D. | $y=\sqrt{x+1}\sqrt{x-1}$与$y=\sqrt{{x^2}-1}$ |