2.10月9日新浪网报道,2015年全球大米产量为4.7576亿吨,比2014年下降0.59%.某天王阿姨在超市买了10斤大米,她又打算买些小米,看过小米的价钱后,她发现,买8斤小米的总费用比买10斤大米的贵13元;买4斤小米的总费用比买10斤大米的便宜5元,则每斤小米的价钱为( )
| A. | 4.5元 | B. | 4元 | C. | 3.5元 | D. | 3元 |
1.如果A=-x2+4x-1,B=-x2-4x+1,那么B-A等于 ( )
0 297505 297513 297519 297523 297529 297531 297535 297541 297543 297549 297555 297559 297561 297565 297571 297573 297579 297583 297585 297589 297591 297595 297597 297599 297600 297601 297603 297604 297605 297607 297609 297613 297615 297619 297621 297625 297631 297633 297639 297643 297645 297649 297655 297661 297663 297669 297673 297675 297681 297685 297691 297699 366461
| A. | -2x2 | B. | 8x-2 | C. | 2-8x | D. | 0 |