Salut,
[tex]a-\dfrac{1}a=3,\ ridic\breve{a}m\ totul\ la\ p\breve{a}trat,\ membru\ cu\ membru:\\\\\left(a-\dfrac{1}a\right)^2=3^2\Leftrightarrow a^2-2\cdot a\cdot\dfrac{1}a+\left(\dfrac{1}a\right)^2=9\Leftrightarrow \\\\\Leftrightarrow a^2-2+\dfrac{1}{a^2}=9\Rightarrow a^2+\dfrac{1}{a^2}=11.[/tex]
Ai înțeles rezolvarea ?
Green eyes.
