Question

a=(2+radical din 3)totul la 2 - radical din 2(RADICAL 5+radical 3)-2 radical 3(2-radical2)+radical2(radical5-radical 3)

Aratati ca a apartine lui N

Answer 1

2+$( 2+\sqrt{3}) ^{2} - \sqrt{2}( \sqrt{3}+ \sqrt{5})-2 \sqrt{3}(2- \sqrt{2})+ \sqrt{2}( \sqrt{5}- \sqrt{3} )=$ 
$4+4 \sqrt{3}+3- \sqrt{10} - \sqrt{6} -4 \sqrt{3}+2 \sqrt{6}+ \sqrt{10}- \sqrt{6} = \\ 4+3=7$