Salut,
[tex]\left(x-\dfrac{1}x\right)^2=x^2-2\cdot x\cdot\dfrac{1}x+\left(\dfrac{1}x\right)^2\Leftrightarrow\\\\\Leftrightarrow 3^2=x^2-2+\dfrac{1}{x^2}\Leftrightarrow x^2+\dfrac{1}{x^2}=11.[/tex]
Ai înțeles rezolvarea ?
Green eyes.
