A.当x<1时,y随x的增大而减小 | B.它的图象与x轴有交点 |
C.当1<x<3时,y>0 | D.顶点坐标为(2,-1 ) |
销售单价(元) | 50 | 53 | 56 | 59 | 62 | 65 |
月销售量(千克) | 420 | 360 | 300 | 240 | 180 | 120 |
A.(2,-3) | B.(-2,3) | C.(2,3) | D.(-2,-3) |
A.(2,4) | B.(-2,-4) | C.(-4,2) | D.(4,-2) |
A.abc>0 | B.3a +c<0 | C.4a+2b+c<0 | D.b2 -4ac<0 |
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