14-6√5-6√(9-2·3·√5+(√5)²)=14-6√5-6√(3-√5)²=14-6√5-6|3-√5|=
=14-6√5-6(3-√5)=14-6√5-18+6√5=-4
|3-√5|=3-√5 т.к. 3>√5 3-√5>0
14-6 \sqrt{5 } -6 \sqrt{14-6 \sqrt{5}} = 14-6 \sqrt{5-6 \sqrt{(3-\sqrt{5})