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2016年天津中考卷第25题的第一问中求抛物线的顶点坐标可根据顶点坐标公式或配方化为顶点式求得;第二问中的第一小问因抛物线向上平移,所以二次项系数不变,顶点的横坐标不变,一次项系数不变,于是设C’的解析式为y=x~2-2x+c或y=(x-1)~2+k’,第二小问要设法突破点K的坐标,可求K的坐标或将K的坐标待定,前者重“形”的破译,后者重解析之法,还可将A的坐标待定,此问是该题的压轴所在.
In the first question of Tianjin Questionnaire 25 in 2016, the coordinates of the vertices of the founding parabola can be obtained according to the vertex coordinate formula or formulation as the vertex; the first minor in the second question is translated upward by the parabola, so the quadratic term The coefficient is constant, the abscissa of the vertex is invariable, the coefficient of the first term is invariable, and then the analytic expression of C ’is y = x ~ 2-2x + c or y = (x-1) ~2 + k’ Small asked to try to break through the coordinates of the point K, can seek the coordinates of K or the coordinates of K to be determined, the former heavy “Shaped ” deciphering, the latter method of parsing, but also the coordinates of A to be determined, this question is The title of the finale.