1.(-2m-1)2=( )
| A. | 4m2+1 | B. | 4m2-1 | C. | 4m2+4m+1 | D. | 4m2-4m+1 |
20.若x2-x-m=(x+n)(x+7),则m-n=( )
| A. | -64 | B. | -48 | C. | 48 | D. | 64 |
19.
如图,在平面直角坐标系中,直线y=-2x和y=ax+4相交于点A(m,3),则不等式-2x<ax+4的解集为( )
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| A. | x<-$\frac{3}{2}$ | B. | x<3 | C. | x>-$\frac{3}{2}$ | D. | x>3 |