对于一元二次方程ax2+bx+c=0(a≠0),当判别式Δ=b2-4ac≥0时,若两根为x1、x2,则两根与一元二次方程的系数关系为:x1+x2=-ba,x1·x2=ca,根与系数的这种关系又称为韦达定理;它的逆定理也是成立的,即当x1+x2=-ba,x1·x2=ca时,那么x1、x2则是ax2+bx+c=0(a≠0)的两根.一元二次方程的根与系数的关系,综合性强,应用极为广泛,在初中数学中占有极重要的地位,也是数学学习中的重点,更是中考试 For the quadratic equation ax2 + bx + c = 0 (a ≠ 0), when the discriminant Δ = b2-4ac ≥ 0, if the two are x1, x2, the relationship between the two and the quadratic equation is : x1 + x2 = -ba, x1 · x2 = ca, and the relationship between root and coefficient is also called Veda’s theorem. The inverse theorem holds for x1 + x2 = -ba, x1 · x2 = ca , Then x1 and x2 are two of ax2 + bx + c = 0 (a ≠ 0). The relationship between the root and coefficient of the quadratic equation is comprehensive and has a very wide range of applications and plays a very important role in junior high school mathematics Position, but also the focus of mathematics learning, but also in the examination