题目

．(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． 答案：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

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