一、知识梳理1.已知二次函数y=ax~2+bx+c(a≠0)的值等于m,求自变量x的值,可以解一元二次方程ax~2+bx+c=m(即ax~2+bx+c-m=0).反过来,解方程ax~2+bx+c=0(a≠0)可以看做已知二次函数y=ax~2+bx+c的值为0,求自变量x的值.2.二次函数y=ax~2+bx+c(a≠0)与一元二次方程ax~2+bx+c=0(a≠0)的关系:当b~2-4ac>0时,一元二次方程ax~2+bx+c=0(a≠ First, the knowledge combing 1 known quadratic function y = ax ~ 2 + bx + c (a ≠ 0) is equal to the value of m, seeking the value of the variable x can be solved quadratic equation ax ~ 2 + bx + c the equation ax ~ 2 + bx + c = 0 (a ≠ 0) can be seen as a known quadratic function y = ax ~ 2 + bx + The value of c is 0 and the value of the independent variable x is found. 2. The quadratic function y = ax ~ 2 + bx + c (a ≠ 0) and the quadratic equation ax ~ 2 + bx + c = 0 ): When b ~ 2-4ac> 0, the quadratic equation ax ~ 2 + bx + c = 0 (a ≠