题目内容
．(6分) 已知二次函数
的图象与y轴交于点A(0，－6)，与x轴的一个交点坐标是B(－2，0)．(1)求二次函数的关系式，并写出顶点坐标；
(2)将二次函数图象沿x轴向左平移
个单位长度，求所得图象对应的函数关系式．
解：（1）把A(O，-6)代入y=x2+bx+c求得
···························································（1分）
把B(-2，0)代入y=x2+bx-6求得
··························································（2分）
所以
················································································（3分）
所以顶点坐标
····························································································（4分）
(2)二次函数图象沿x轴向左平移个单位长度得：
··············（6分）解析:
略
···························································（1分）把B(-2，0)代入y=x2+bx-6求得
··························································（2分）所以
················································································（3分）所以顶点坐标
····························································································（4分）(2)二次函数图象沿x轴向左平移
个单位长度得： ··············（6分）解析:略
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