下面三种情形,常常借用二次方程来求解: 第一种情形:如果条件式含有两个结构相同的二次式,则可考虑利用方程的定 义构造二次方程来解答, 例1 设 求 的值. 分析 由于两个条件式 结构相同,故可构造二 次方程 则a1,a2是这个二次方程的两个不等实根,从而 .显然,在此式中令x=-b1,则可得所求的值为-1.(解答略) The following three cases are often solved by using the quadratic equation: Case 1: If the conditional expression contains two quadratic structures with the same structure, you can consider using the definition of the equation to construct a quadratic equation to solve the problem. Example 1 Values. Since the two conditional structures are the same, the quadratic equations a1 and a2 can be constructed as two unequal real roots of the quadratic equation. Thus, it is clear that in this equation, if x=-b1, then The required value is -1. (Solution omitted)