[tex]x=-\sqrt{5}\\\\2 \sqrt{5}( \sqrt{5} - x) - 3x (x^2-4 \sqrt{5}) =2 \sqrt{5}( \sqrt{5} - (-\sqrt{5})) - 3*(-\sqrt{5}) ( (-\sqrt{5})^2-4 \sqrt{5}) =\\\\= 2 \sqrt{5} * 2\sqrt{5} +3\sqrt{5} * ( 5-4 \sqrt{5}) = 4*5+15\sqrt{5}-12*5=20+15\sqrt{5}-60=\\\\=15\sqrt{5}-40[/tex]
