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Se considera numarul x apartine R* Daca X-1/x = 4 , calculati x^2 + 1/x^2​

Răspuns :

Salut,

[tex]x-\dfrac{1}x=4\ (\ )^2\Rightarrow\left(x-\dfrac{1}x\right)^2=16\Leftrightarrow x^2-2\cdot x\cdot\dfrac{1}x+\left(\dfrac{1}x\right)^2=16\Leftrightarrow\\\\\Leftrightarrow x^2-2+\dfrac{1}{x^2}=16,\ deci\ \boxed{x^2+\dfrac{1}{x^2}=18.}[/tex]

Green eyes.