抛物线是轴对称图形,解答某些与抛物线有关的问题,若利用抛物线的对称性,可使问题迅速获解.一、求顶点坐标例1(2013年徐州)二次函数y=ax~2+bx+c图象上部分点的坐标满足表1.解析:观察表格发现:当x=-3时y=-3;当x=-1时y=-3.因为点(-3,-3)与(-1,-3)的纵坐标相同,所以它们是抛物线上的一组对称点,于是抛物线的 The parabola is an axisymmetric graph that solves some problems related to parabola. If the symmetry of the parabola is used, the problem can be solved quickly. First, find the vertex coordinates Example 1 (Xuzhou, 2013) Quadratic function y=ax~2+ The coordinates of some of the points on the bx+c image satisfies Table 1. Resolution: observation table found: when x=-3, y=-3; when x=-1, y=-3. because of the point (-3,-3) ) are the same as the ordinates of (-1,-3), so they are a set of symmetry points on the parabola, so parabolic