Question

Sa simplific fractia :

5x^2 -9
-------------
radical 5x +3 (doar 5 sub radical)

Answer 1

$5 x^{2} -9=( \sqrt{5} x-3) (\sqrt{5}x+3)$ 
Cea de mai sus e formula de calcul precurtat
Deci fractia devine
$\frac{ (\sqrt{5}x-3)( \sqrt{5}x+3) }{ \sqrt{5}x+3 }$
Dupa simplificare (este evidenta) ramane $\sqrt{5}x-3$