Question

Ajutatima sa calculez acest exercvitiu pe lung va rog 

Answer 1

      
$( \frac{2}{5}-2 \sqrt{3})( \frac{2}{5}+2 \sqrt{3})+(-\frac{2}{5}-2 \sqrt{3})(\frac{2}{5}+2 \sqrt{3})= \\ \\ = ( \frac{2}{5}-2 \sqrt{3})( \frac{2}{5}+2 \sqrt{3})-(\frac{2}{5}+2 \sqrt{3})(\frac{2}{5}+2 \sqrt{3})=\\ \\ = ( (\frac{2}{5})^{2}-(2 \sqrt{3})^{2})-(\frac{2}{5}+2 \sqrt{3})^{2}= \\ \\ = ( \frac{4}{25}-12) -((\frac{2}{5})^{2}+2(\frac{2}{5}*2 \sqrt{3}) +(2 \sqrt{3})^{2})= \\ \\ =( \frac{4}{25}-12) -(\frac{4}{25} +\frac{8\sqrt{3}}{5} + 12 )=$
        
$=\frac{4}{25}-12 -\frac{4}{25} -\frac{8\sqrt{3}}{5} - 12 = \\ \\ = -24 - \frac{8 \sqrt{3} }{5}$