一元二次方程中有不少求值的问题,这类问题中量与量之间的关系不是十分明显,如果能利用一元二次方程根与系数关系构造方程,就能比较清楚揭示内在关系易于获解． 1．由根的关系求方程例1 已知方程x2+ax+b=0的两根分别为x1,x2,且x13+x23=19,x1+x2=-1,求此方程． 解 There are many problems in the evaluation of quadratic equations. The relationship between quantity and quantity is not very obvious in this type of problem. If one can use the equation of the quadratic equation of one yuan to construct the equation, it can be clearly revealed that the internal relations are easy to understand. Get settled. 1. Find the equation 1 from the relationship between the roots. The two known equations x2 + ax + b = 0 are x1, x2, and x13 + x23 = 19, x1 + x2 = -1. Find this equation. solution