Question

aratati ca numarul:a=2(8+√18)-3(4+√8) este intreg

Answer 1

a=16+2√18-12-3√8
a=16+6√2-12-6√2
a=4    
4 ∈Z

Answer 2

$a=2(8+ \sqrt{18} )-3(4+ \sqrt{8} ) \\ a=2(8+3 \sqrt{2} )-3(4+2 \sqrt{2} ) \\ a=16+6 \sqrt{2} -12-6 \sqrt{2} \\ a=16-12 \\ a=4 \in Z$