Question

$(2 \sqrt{5} + \sqrt{2} ) ^{2} - (2 \sqrt{5} - \sqrt{2} ) ^{2} +(2 \sqrt{5} + \sqrt{2} )(2 \sqrt{5} - \sqrt{2} )$

Answer 1

(2√5+√2)²-(2√5-√2)²+(2√5+√2)(2√5-√2)=
=(2√5+√2-2√5+√2)(2√5+√2+2√5-√2)+(4×5-2)=
=2√2×4√5+18=
=8√10+18