[tex]\displaystyle\bf\\x^{2} +2x-3=0\\\\x_{1} =-3 \ \ ; \ \ x_{2} =1\\\\x^{2} +2x-3\geq 0\\\\\Big(x+3\Big)\Big(x-1\Big)\geq 0[/tex]

+ + + + + [- 3] - - - - - [1] + + + + +

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Ответ : x ∈ ( - ∞ : - 3]  ∪  [1 ; + ∞)