8.某人购进一批苹果,到市场零售,已知销售额y(元)与卖出的苹果数量x(千克)的关系如表所示,则y与x之间的关系式为y=3.6x
| 数量x(千克) | 2 | 3 | 4 | 5 | … |
| 销售额y(元) | 7.2 | 10.8 | 14.4 | 18.0 | … |
7.下列分解因式正确的是( )
| A. | x2-x=x(x2-1) | B. | m2+m+$\frac{1}{4}$=(m+$\frac{1}{2}$)2 | C. | (a+4)(a-4)=a2-16 | D. | x2+y2=(x+y)(x-y) |
6.计算$\sqrt{8}$-$\sqrt{2}$的结果是( )
0 287278 287286 287292 287296 287302 287304 287308 287314 287316 287322 287328 287332 287334 287338 287344 287346 287352 287356 287358 287362 287364 287368 287370 287372 287373 287374 287376 287377 287378 287380 287382 287386 287388 287392 287394 287398 287404 287406 287412 287416 287418 287422 287428 287434 287436 287442 287446 287448 287454 287458 287464 287472 366461
| A. | $\sqrt{2}$ | B. | -$\sqrt{2}$ | C. | $\sqrt{6}$ | D. | 2 |