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Sa-mi spuneti cum ati facut. :)


Sami Spuneti Cum Ati Facut class=

Răspuns :

folosesti formula de calcul prescurtat
 (a+1/a)²=a²+2a*1/a+(1/a)²=a²+(1/a)²+2=7+2=9
[tex]a^2+\dfrac{1}{a^2}=27\Rightarrow a^2+2\cdot a\cdot\dfrac{1}{a}+\dfrac{1}{a^2}=7+2[/tex]

[tex](a+\dfrac1a)^2=9\Rightarrow a+\dfrac1a=\pm3[/tex]