7.
如图:在△ABC中,∠C=90°,AC=BC,D是AC上一点,AE⊥BD交BD的延长线于E,且AE=$\frac{1}{2}$BD,DF⊥AB于F,AE,BC的延长线相交于点G.求证:CD=DF.
6.下列多项式中,可以提取公因式的是( )
0 290343 290351 290357 290361 290367 290369 290373 290379 290381 290387 290393 290397 290399 290403 290409 290411 290417 290421 290423 290427 290429 290433 290435 290437 290438 290439 290441 290442 290443 290445 290447 290451 290453 290457 290459 290463 290469 290471 290477 290481 290483 290487 290493 290499 290501 290507 290511 290513 290519 290523 290529 290537 366461
| A. | x2-y2 | B. | x2+x | C. | x2-y | D. | x2+2xy+y2 |