13.下列各式计算正确的是( )
| A. | $\sqrt{(2-\sqrt{5})^{2}}$=2-$\sqrt{5}$ | B. | 5$\sqrt{3}$+5$\sqrt{2}$=10$\sqrt{5}$ | C. | 4$\sqrt{3}$×2$\sqrt{2}$=8$\sqrt{6}$ | D. | 4$\sqrt{2}$÷2$\sqrt{2}$=2$\sqrt{2}$ |
12.下列各式属于因式分解的是( )
| A. | a(x+y)=ax+ay | B. | x2-4x+4=x(x-4)+4 | ||
| C. | 10x2-5x=5x(2x-1) | D. | x2-16x+6x=(x+4)(x-4)+6x |
8.下列运算不正确的是( )
0 285396 285404 285410 285414 285420 285422 285426 285432 285434 285440 285446 285450 285452 285456 285462 285464 285470 285474 285476 285480 285482 285486 285488 285490 285491 285492 285494 285495 285496 285498 285500 285504 285506 285510 285512 285516 285522 285524 285530 285534 285536 285540 285546 285552 285554 285560 285564 285566 285572 285576 285582 285590 366461
| A. | 2a3÷a=2a2 | B. | ($\sqrt{2}$-1)0=0 | C. | $\root{3}{8}$=2 | D. | (ab2)2=a2b4 |