For any real numbers \(x,y\in\mathbb R\), the following reverse triangle inequalities hold:
$(1)$ $|x+y|\ge |x|-|y|,$
$(2)$ $|x-y|\ge \left||x|-|y|\right|,$
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| created: 2017-03-19 12:25:53 | modified: 2017-03-19 12:32:20 | by: bookofproofs | references: [581]
[581] Forster Otto: “Analysis 1, Differential- und Integralrechnung einer Veränderlichen”, Vieweg Studium, 1983