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不等式:(Ⅰ)|a+b|≤|a|+|b|,(Ⅱ)|a-b|≥|a|-|b|,(Ⅲ)||a|-|b||≤|a-b|是大家所熟知的。但这些非严格不等式在什么时候等号成立?下面看等号成立的条件。
Inequality: (I)|a+b|≤|a|+|b|,(II)|ab|≥|a|-|b|, (III)||a|-|b||≤|ab| It is well known to everyone. But when are these non-strict inequality equations established? Let’s look at the conditions for the establishment of equal signs.