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在数的许多概念中,绝对值概念占有重要地位,是初中数学教学中的一个难点。本文试图综合出初中数学中关于绝对值问题的应对策略,以供读者参考。 一、简单应用定义 我们知道,如果a≥0,那么|a|=a,如果a≤0,那么|a|=-a。 例1 三个有理数a、b、c,其积是负数,其和是正数,当x=|a|/a+|b|/b+|c|/c时,试求代数式x~(19)-92x+2的值。(第二届“勤奋杯”全国初中数学邀请赛题)
In many concepts of numbers, the concept of absolute value occupies an important position and is a difficulty in mathematics teaching in junior middle school. This article attempts to synthesize the coping strategies of absolute mathematics in junior high school mathematics for readers’ reference. First, the simple application of the definition We know that if a ≥ 0, then | a | = a, if a ≤ 0, then | a | = - a. Example 1 Three rational numbers a, b, c whose product is negative and whose sum is positive. When x=|a|/a+|b|/b+|c|/c, try the algebraic expression x~(19)- 92x+2 value. (The second “Diligence Cup” national junior high school mathematics invitational contest title)