5.下列运算结果正确的是( )
| A. | $\frac{a}{b}$÷$\frac{c}{d}$=$\frac{ac}{bd}$ | B. | $\frac{b}{a-b}$+$\frac{a}{b-a}$=1 | ||
| C. | ($\frac{2a}{a-b}$)2=$\frac{4{a}^{2}}{{a}^{2}-{b}^{2}}$ | D. | $\frac{{m}^{4}}{{n}^{5}}$•$\frac{{n}^{4}}{{m}^{3}}$=$\frac{m}{n}$ |
3.已知(x-2y-1)2+|2x+y-7|=0,则3x-y=( )
| A. | 3 | B. | 1 | C. | 8 | D. | -6 |
1.下列各式不能用平方差公式法分解因式的是( )
| A. | x2-4 | B. | -x2-y2+2xy | C. | m2n2-1 | D. | a2-4b2 |
16.若$\sqrt{1-2x}$有意义,则x的取值范围( )
0 283680 283688 283694 283698 283704 283706 283710 283716 283718 283724 283730 283734 283736 283740 283746 283748 283754 283758 283760 283764 283766 283770 283772 283774 283775 283776 283778 283779 283780 283782 283784 283788 283790 283794 283796 283800 283806 283808 283814 283818 283820 283824 283830 283836 283838 283844 283848 283850 283856 283860 283866 283874 366461
| A. | x>2 | B. | x≤$\frac{1}{2}$ | C. | x≠$\frac{1}{2}$ | D. | x≤2 |