2.若$\left\{\begin{array}{l}{x=2}\\{y=1}\end{array}\right.$是方程组$\left\{\begin{array}{l}{kx-my=1}\\{mx+ky=8}\end{array}\right.$的解,则k,m的值为( )
| A. | $\left\{\begin{array}{l}{k=2}\\{m=3}\end{array}\right.$ | B. | $\left\{\begin{array}{l}{k=2}\\{m=-3}\end{array}\right.$ | C. | $\left\{\begin{array}{l}{k=3}\\{m=2}\end{array}\right.$ | D. | $\left\{\begin{array}{l}{k=-3}\\{m=-2}\end{array}\right.$ |
1.下面分别是四个同学在解方程$\frac{1}{2}$-$\frac{x-3}{3}$=1时的去分母的第一步,其中正确的是( )
| A. | 1-2(x-3)=1 | B. | 3-2(x-3)=1 | C. | 1-2(x-3)=6 | D. | 3-2(x-3)=6 |
20.下列各对数值,是方程2x-3y=6的解是( )
| A. | $\left\{\begin{array}{l}{x=0}\\{y=4}\end{array}\right.$ | B. | $\left\{\begin{array}{l}{x=1}\\{y=-2}\end{array}\right.$ | C. | $\left\{\begin{array}{l}{x=2}\\{y=-1}\end{array}\right.$ | D. | $\left\{\begin{array}{l}{x=3}\\{y=0}\end{array}\right.$ |
19.下列方程的变形正确的是( )
0 284597 284605 284611 284615 284621 284623 284627 284633 284635 284641 284647 284651 284653 284657 284663 284665 284671 284675 284677 284681 284683 284687 284689 284691 284692 284693 284695 284696 284697 284699 284701 284705 284707 284711 284713 284717 284723 284725 284731 284735 284737 284741 284747 284753 284755 284761 284765 284767 284773 284777 284783 284791 366461
| A. | 由3+x=5,得x=5+3 | B. | 由7x=-3,得x=-$\frac{7}{3}$ | C. | 由2y=0,得y=$\frac{1}{2}$ | D. | 由-2x-6=0得x=-3 |