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在一次数学测试中,有一道填空题和一道解答题:例1.若x=-x,则x满足____。学生答:x≤0。2.x是数轴上的一个数,试讨论:x为有理数时,|x+1|+|x-2|是否存在最小值?若存在,求出这个最小值;若不存在,请说明理由。学生解答:不存在。因为任何数的绝对值都是非负数。如果|x+1|+|x-2|这个式子有最小值,那么这个最小值就是0;经过计算得x=-1和x=2。因为x的值不相等,所以没有最小值。
In a math test, there is a blank fill question and an answer: Example 1. If x = -x then x satisfies ____. Student A: x≤0.2.x is a number on the axis, try to discuss: x is a rational number, | x +1 | + | x-2 | is there a minimum? If present, find the minimum; If not, please explain the reasons. Student Answer: does not exist. Because the absolute value of any number is non-negative. If | x + 1 | + | x-2 | has the smallest value for this expression, then this minimum is zero; and x = -1 and x = 2 are calculated. Since the value of x is not equal, there is no minimum.