13.一列快车长306m,一列慢车长344m,两车相向而行,从相遇到离开需要13s,如果同向而行,快车从追及到超过慢车需要65s,求快车、慢车各自的速度.若设快车速度为x m/s,慢车速度为y m/s,那么,由题意列出的方程为( )
| A. | $\left\{\begin{array}{l}13(x+y)=306+344\\ 65(x-y)=344\end{array}$ | B. | $\left\{\begin{array}{l}13(x+y)=306+344\\ 65(x-y)=344+306\end{array}$ | ||
| C. | $\left\{\begin{array}{l}13(x+y)=306+344\\ 65(x-y)=344-306\end{array}$ | D. | $\left\{\begin{array}{l}344y=306x\\ 65(x-y)=344+306\end{array}$ |
10.
如图,把一个矩形纸片ABCD沿AD和BC的中点连线EF对折,要使矩形AEFB与原矩形相似,则原矩形长与宽的比为( )
| A. | 2:1 | B. | 3:1 | C. | $\sqrt{2}$:1 | D. | 4:1 |
9.有一块多边形草坪,在市政建设设计图纸上的面积为300cm2,其中一条边的长度为5cm,经测量,这条边的实际长度为15m,则这块草坪的实际面积是( )
0 308547 308555 308561 308565 308571 308573 308577 308583 308585 308591 308597 308601 308603 308607 308613 308615 308621 308625 308627 308631 308633 308637 308639 308641 308642 308643 308645 308646 308647 308649 308651 308655 308657 308661 308663 308667 308673 308675 308681 308685 308687 308691 308697 308703 308705 308711 308715 308717 308723 308727 308733 308741 366461
| A. | 100m2 | B. | 270m2 | C. | 2 700m2 | D. | 90 000m2 |