Salutare !!!
[tex]\bf x-\dfrac{1}{x} = 4\:\:\:|(\:)^{2}[/tex] ridicam fiecare membru la patrat
[tex]\bf \Big(x-\dfrac{1}{x}\Big)^{2} = 4^{2}[/tex]
[tex]\bf x^{2}-2\cdot x \cdot \dfrac{1}{x} +\Big(\dfrac{1}{x}\Big)^{2} = 16[/tex]
[tex]\bf x^{2}-2\cdot\not x \cdot \dfrac{1}{\not x} +\dfrac{1}{x^{2}} = 16[/tex]
[tex]\bf x^{2}-2 +\dfrac{1}{x^{2}} = 16[/tex]
[tex]\bf x^{2} +\dfrac{1}{x^{2}} = 16 +2[/tex]
[tex]\boxed{\bf x^{2} +\dfrac{1}{x^{2}} = 18}[/tex] x ∈ R*
≈≈≈≈ Mult succes ! ≈≈≈≈
