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“±”号是正号“+”和负号“一”的合写,由于使用的对象和搭配关系不同,两符号之间的关系也不一样,今分辨如下。 1.原命题中,是“或”关系。如x=±1时,等式x~2=1成立。详细点说就是X=1或x=-1时,等式成立。 2.否命题中,是“且”关系。实数x≠±1时,不等式x~2≠1成立。详细点说就是x≠1且x≠-1时,不等式x~2≠1成立。 3.集合中,是“和”关系。方程x~2-4=0的两个根是±2。详细点说就是:方程x~2-4=0的两个根是+2和-2。
The “±” sign is a combination of positive sign “+” and negative sign “1”. Since the objects and collocations used are different, the relationship between the two signs is also different. 1. The original proposition is the “or” relationship. If x=±1, the equation x~2=1 holds. In more detail, when X=1 or x=-1, the equation holds. 2. No propositions are “and” relations. When the real number x≠±1, the inequality x~2≠1 holds. In more detail, when x≠1 and x≠-1, the inequality x~2≠1 holds. 3. In the collection, it is the “and” relationship. The two roots of the equation x~2-4=0 are ±2. In more detail, the two roots of the equation x~2-4=0 are +2 and -2.