14.
如图,将AB=4,BC=8的矩形纸片ABCD折叠,使点C与点A重合,则折痕EF的长是( )
| A. | $\sqrt{3}$ | B. | 2$\sqrt{3}$ | C. | $\sqrt{5}$ | D. | 2$\sqrt{5}$ |
13.在用代入消元法解方程组$\left\{\begin{array}{l}{3x+y=-9}\\{4x-3y=3}\end{array}\right.$时,消去未知数y后,得到的方程为( )
| A. | 4x-3(-9-3x)=3 | B. | 4x+3(-9-3x)=3 | C. | 4x-3(-9+3x)=3 | D. | 4x+3(-9+3x)=3 |
10.方程4x-1=3的解是( )
0 294505 294513 294519 294523 294529 294531 294535 294541 294543 294549 294555 294559 294561 294565 294571 294573 294579 294583 294585 294589 294591 294595 294597 294599 294600 294601 294603 294604 294605 294607 294609 294613 294615 294619 294621 294625 294631 294633 294639 294643 294645 294649 294655 294661 294663 294669 294673 294675 294681 294685 294691 294699 366461
| A. | x=1 | B. | x=-1 | C. | x=2 | D. | x=-2 |