12.下列计算正确的是( )
| A. | a3÷a2=a | B. | (-2a2)3=8a6 | C. | 2a2+a2=3a4 | D. | (a-b)2=a2-b2 |
11.在-1,0,2,$\sqrt{2}$四个数中,最大的数是( )
| A. | -1 | B. | 0 | C. | 2 | D. | $\sqrt{2}$ |
5.用长为16m的木条围成一个矩形框架,设矩形面积为S(m2),则S的最大值为( )
0 279331 279339 279345 279349 279355 279357 279361 279367 279369 279375 279381 279385 279387 279391 279397 279399 279405 279409 279411 279415 279417 279421 279423 279425 279426 279427 279429 279430 279431 279433 279435 279439 279441 279445 279447 279451 279457 279459 279465 279469 279471 279475 279481 279487 279489 279495 279499 279501 279507 279511 279517 279525 366461
| A. | 8m2 | B. | 16m2 | C. | 12m2 | D. | 32m2 |