二次函数式与二次函数的图象的关系是很多省市每年中考必考的内容,下面举一些省市中考题中有关二次函数图象对二次函数的判断的例子.分析从以下的选择题中可以看出:结合图象和二次函数的式子y=ax~2+bx+c(a≠0)可以得出一些结论:(1)a>0,函数图象开口向上,a<0,函数图象开口向下.(2)c>0,函数图象交与y轴正半轴, Quadratic function and the quadratic function of the image is a lot of provinces and cities in the annual test will be the content of the exam, some provinces and cities in the following test questions on the quadratic function of the image to determine the quadratic function example.Analysis from the following (1) a> 0, the opening of the function image is upwards , a <0, the function image is open downward. (2) c> 0, the function image is intersected with the positive semi-axis of the y-axis,