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在解与实数相关的问题时,常常用到一元二次方程ax2+bx+c=0(a≠0)的根的判别式△=b2-4ac,这里谈谈判别式的具体应用中的一些错解。一、待定系数的求值问题例1.已知关于x的方程x2-mx-n=0的两根的积比两根之和的2倍小12,并且两根的平方和为22,求m,n的值。错解:设两根分别为x1、x2
In solving problems related to real numbers, the discriminant △=b2-4ac of the root of the one-dimensional quadratic equation ax2+bx+c=0(a≠0) is often used. Some of the specific applications of the negotiation type are discussed here. Misunderstanding. First, the problem of the evaluation of the undetermined coefficient Example 1. Know that the product of the two x2-mx-n = 0 of the equation x is less than 2 times the sum of the two roots of the 12 and the sum of the squares of the two is 22, find The value of m,n. Misunderstanding: Let two roots be x1, x2 respectively