11.下列运算中,正确的是( )
| A. | 3a-2a=a | B. | (a2)3=a5 | C. | a2•a3=a6 | D. | a10÷a5=a2 |
10.把0.00065用科学记数法表示为( )
0 283501 283509 283515 283519 283525 283527 283531 283537 283539 283545 283551 283555 283557 283561 283567 283569 283575 283579 283581 283585 283587 283591 283593 283595 283596 283597 283599 283600 283601 283603 283605 283609 283611 283615 283617 283621 283627 283629 283635 283639 283641 283645 283651 283657 283659 283665 283669 283671 283677 283681 283687 283695 366461
| A. | -6.5×103 | B. | 0.65×10-3 | C. | -6.5×104 | D. | 6.5×10-4 |