二次函数是初中数学的重点也是难点,特别是二次函数综合题更使一部分学生感到十分棘手,下面举例说明处理二次函数综合问题的常用方法．例1 已知第一象限内的点P(a,b)在直线 y=(12/5)x上,且二次函数y=(c-a)x2+2bx+ a+c的图象的顶点在x轴上,求a:b:c的值．解因为点P(a,b)在直线y=(12/5)x上, The quadratic function is the key and difficult point in the junior high school mathematics, especially the quadratic function synthesis problem makes some students feel very difficult. The following examples illustrate the common methods of dealing with the quadratic function synthesis problem. Example 1 It is known that the point P(a,b) in the first quadrant is on the line y=(12/5)x, and the vertex of the image of the quadratic function y=(ca)x2+2bx+a+c is at the x On the axis, find the value of a:b:c. The solution is because the point P(a,b) is on the straight line y=(12/5)x,