摘要：013]解:(1)该抛物线过点.可设该抛物线的解析式为． 将.代入. 得解得 此抛物线的解析式为．························································ (2)存在．··········································································································· 如图.设点的横坐标为. 则点的纵坐标为. 当时. .． 又. ①当时. . 即． 解得.．····························································· ②当时..即． 解得. 当时.．················································································· 类似地可求出当时.．································································· 当时.． 综上所述.符合条件的点为或或．······························ (3)如图.设点的横坐标为.则点的纵坐标为． 过作轴的平行线交于．由题意可求得直线的解析式为． 点的坐标为．．·· ． 当时.面积最大．．····················································
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已知直线y＝－2x＋b(b≠0)与x轴交于点A，与y轴交于点B；一抛物线的解析式为y＝x2－(b＋10)x＋c．
(1)若该抛物线过点B，且它的顶点P在直线y＝－2x＋b上，试确定这条抛物线的解析式；
(2)过点B作直线BC⊥AB交x轴于点C，若抛物线的对称轴恰好过C点，试确定直线y＝－2x＋b的解析式．
已知直线y＝－2x＋b(b≠0)与x轴交于点A，与y轴交于点B；一抛物线的解析式为y＝x2－(b＋10)x＋c．
(1)若该抛物线过点B，且它的顶点P在直线y＝－2x＋b上，试确定这条抛物线的解析式；
(2)过点B作直线BC⊥AB交x轴交于点C，若抛物线的对称轴恰好过C点，试确定直线y＝－2x＋b的解析式．
解答题
已知直线y＝－2x＋b(b≠0)与x轴交于点A，与y轴交于点B，一抛物线的解析式为y＝x2－(b＋10)x＋c．
(1)若该抛物线过点B，且它的顶点P在直线y＝－2x＋b上，试确定这条抛物线的解析式；
(2)过点B作直线BC⊥AB交x轴于点C，若抛物线的对称轴恰好过点C，试确定直线y＝－2x＋b的解析式．
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（2013•建宁县质检）如图：已知抛物线