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应用二次方程根的判别式解题,不可忽视其适用的前提条件,否则,就会出现这样或那样的错误。现举例说明。例1 求函数y=(x~2+x+1)/(3x~2+3x)的值域。
Applying the discriminant formula of the root of the quadratic equation can not ignore its applicable preconditions, otherwise, it will appear this or that error. Here is an example. Example 1 Find the range of the function y=(x~2+x+1)/(3x~2+3x).