4.某展厅要用相同的正方体木块搭成一个三视图如下的展台,则搭成此展台共需这样的正方体( )

| A. | 5个 | B. | 4个 | C. | 6个 | D. | 3个 |
2.已知二次函数y=ax2+bx+c中,函数y与自变量x的部分对应值,如表:
(1)求二次函数解析式?
(2)当x为何值,y有最小值,最小值是多少?
(3)若m<0,点A(m,y1)B(m+1,y2)都在该函数图象上,试比较y1、y2的大小.
0 286533 286541 286547 286551 286557 286559 286563 286569 286571 286577 286583 286587 286589 286593 286599 286601 286607 286611 286613 286617 286619 286623 286625 286627 286628 286629 286631 286632 286633 286635 286637 286641 286643 286647 286649 286653 286659 286661 286667 286671 286673 286677 286683 286689 286691 286697 286701 286703 286709 286713 286719 286727 366461
| x | … | -1 | 0 | 1 | 2 | 3 | 4 | … |
| y | … | 10 | 5 | 2 | 1 | 2 | 5 | … |
(2)当x为何值,y有最小值,最小值是多少?
(3)若m<0,点A(m,y1)B(m+1,y2)都在该函数图象上,试比较y1、y2的大小.