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Daca  x∈R cu steluta , astfel incat [tex]x+ \frac{1}{x} =4, atunci aflati valoarea sumei x^{2} + \frac{1}{ x^{2} } [/tex]

Răspuns :

[tex]x+ \frac{1}{x} =4[/tex]

ridicam la patrat;

[tex](x+ \frac{1}{x} )^2=4^2[/tex]

[tex] x^{2} + \frac{1}{ x^{2} } +2*x* \frac{1}{x} =16[/tex]

[tex] x^{2} + \frac{1}{ x^{2} } +2=16[/tex]

[tex] x^{2} + \frac{1}{ x^{2} } =14[/tex]