[tex]Aceasta \ este \ formula \ de \ calcul \ prescurtat \ invatata \ in \ generala : \\ \\ (a-b)^{2}=2 ^{2}-2*a*b+b^{2} \\ \\ (2 \sqrt{5}-3 )^{2}=(2 \sqrt{5})^2-2*2 \sqrt{5}*3+3^2 \\ (2 \sqrt{5}-3)^2=20-12 \sqrt{5}+9 \\ (2 \sqrt{5}-3)^2=\boxed{29-12 \sqrt{5}} [/tex]
