16.下列命题:①若点P(x,y)满足xy<0,则点P在第二或第四象限;②两条直线被第三条直线所截,同位角相等;③过已知直线外一点有且只有一条直线与已知直线平行;④当x=0时,式子6-$\sqrt{9-{x}^{2}}$有最小值,其最小值是3;其中真命题的有( )
| A. | ①②③ | B. | ①③④ | C. | ①②③④ | D. | ③④ |
11.下列运算正确的是( )
| A. | (-2xy)(-3xy)3=-54x4y4 | B. | 5a2•(3a3)2=15a12 | ||
| C. | (-0.1x)(-10x2)3=-x2 | D. | (2×10n)(0.5×10n)=102n |
10.已知ax=3,ay=5,则ax+y的值为( )
0 295356 295364 295370 295374 295380 295382 295386 295392 295394 295400 295406 295410 295412 295416 295422 295424 295430 295434 295436 295440 295442 295446 295448 295450 295451 295452 295454 295455 295456 295458 295460 295464 295466 295470 295472 295476 295482 295484 295490 295494 295496 295500 295506 295512 295514 295520 295524 295526 295532 295536 295542 295550 366461
| A. | 8 | B. | 35 | C. | 15 | D. | 53 |