9.若(x+a)2=x2+bx+25,则a,b分别为( )
| A. | a=3,b=6 | B. | a=5,b=5或a=-5,b=-10 | ||
| C. | a=5,b=10 | D. | a=-5,b=-10或a=5,b=10 |
8.(x-2y)(x+2y)的结果是( )
| A. | x2-2y2 | B. | x2-4y2 | C. | x2+4xy+4y2 | D. | x2-4xy+4y2 |
7.(-6xy2)2÷(-3xy)的结果为( )
| A. | -12xy3 | B. | 2y3 | C. | 12xy | D. | 2xy3 |
6.${(-\frac{3}{2})^{-2}}$的结果为( )
| A. | $\frac{9}{4}$ | B. | $-\frac{4}{9}$ | C. | $\frac{4}{9}$ | D. | $-\frac{9}{4}$ |
5.下列运算中正确的是( )
0 284654 284662 284668 284672 284678 284680 284684 284690 284692 284698 284704 284708 284710 284714 284720 284722 284728 284732 284734 284738 284740 284744 284746 284748 284749 284750 284752 284753 284754 284756 284758 284762 284764 284768 284770 284774 284780 284782 284788 284792 284794 284798 284804 284810 284812 284818 284822 284824 284830 284834 284840 284848 366461
| A. | a2+a3=a5 | B. | a3•a4=a7 | C. | 4a2-3a=a2 | D. | a6÷a3=a2 |