利用二次函数图像讨论含参数的实系数一元二次方程根的性质.二次方程ax2+bx+c=0(a≠0)的根即为对应函数f(x)=ax2+bx+c(a≠0)的图像与x轴的交点,解决此类题关键在于设出对应的一元二次函数,根据条件画出图像,然后列出满足题意的充要条件,最后解不等式组得出参数的取值范围,数形结合是 The quadratic function image is used to discuss the properties of the roots of quadratic equations with real coefficients of parameters. The root of the quadratic equation ax2 + bx + c = 0 (a ≠ 0) is the corresponding function f (x) = ax2 + bx + c (a ≠ 0) of the image and the x-axis intersection, the key to solving this problem is to set the corresponding quadratic function, draw the image according to the conditions, and then list the necessary and sufficient conditions to meet the problem, finally solve the inequality group The range of parameters, the number of shape combination is