14.若单项式2xnym-n与单项式3xny2n的和是5xny2n,则m,n的关系是( )
| A. | m=n | B. | m=2n | C. | m=3n | D. | m=4n |
13.符合条件∠A+∠B=∠C的△ABC是( )
0 309643 309651 309657 309661 309667 309669 309673 309679 309681 309687 309693 309697 309699 309703 309709 309711 309717 309721 309723 309727 309729 309733 309735 309737 309738 309739 309741 309742 309743 309745 309747 309751 309753 309757 309759 309763 309769 309771 309777 309781 309783 309787 309793 309799 309801 309807 309811 309813 309819 309823 309829 309837 366461
| A. | 锐角三角形 | B. | 直角三角形 | C. | 钝角三角形 | D. | 不能确定 |