17.下列计算正确的是( )
| A. | a6•a=a7 | B. | (-3ab)2=6a2b2 | C. | a6÷a=a6 | D. | (-bc)4÷(-bc)2=-b2c2 |
13.下列说法不正确的是( )
0 297656 297664 297670 297674 297680 297682 297686 297692 297694 297700 297706 297710 297712 297716 297722 297724 297730 297734 297736 297740 297742 297746 297748 297750 297751 297752 297754 297755 297756 297758 297760 297764 297766 297770 297772 297776 297782 297784 297790 297794 297796 297800 297806 297812 297814 297820 297824 297826 297832 297836 297842 297850 366461
| A. | 平行四边形的对边平行且相等 | B. | 平行四边形对角线互相平分 | ||
| C. | 平行四边形是轴对称图形 | D. | 平行四边形是中心对称图形 |