如图.二次函数y=ax2+bx+c(a>0)与坐标轴交于点A.B.C且OA=1.OB=OC=3 . (1)求此二次函数的解析式. (2)写出顶点坐标和对称轴方程. (3)点M.N在y=ax2+bx+c的图像上.且MN∥x轴.求以MN为直径且与x轴相切的圆的半径. (1)依题意分别代入 1分 解方程组得所求解析式为······································································ 4分 (2)··············································································· 5分 顶点坐标.对称轴················································································· 7分 (3)设圆半径为.当在轴下方时.点坐标为····························· 8分 把点代入得································································· 9分 同理可得另一种情形 圆的半径为或 10分 查看更多

 

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2、本卷第17~25题的9道题中,每道题所赋分数(注:分值依次为6,7,7,8,8,8,9,9,10)的众数和中位数分别是(  )

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21、有一益智游戏分二阶段进行,其中第二阶段共有25题,答对一题得3分,答错一题扣2分,不作答得0分.若小明已在第一阶段得50分,且第二阶段答对了20题,则下列哪一个分数可能是小明在此益智游戏中所得的总分(  )

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一本练习册内有24份练习卷,总共有426道练习题,每份练习卷中有25题或20题或16题.那么这本练习册中有25题的练习卷的份数为(  )
A、1B、2C、3D、4

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一张试卷25题,若做对了一题得4分,做错了一题扣1分,小李做完此卷后得70分,则他做对的题目数是(  )
A、18B、17C、19D、20

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9、一张试卷上有25道选择题:对一道题得4分,错一道得-1分,不做得-1分,某同学做完全部25题得70分,那么它做对题数为(  )

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