2/√10 + 5√2/ 2√5 - ( 2√5 / √8 + 5√2 / √125) = → rationalizam numitorii
= 2√10 /10 + 5√5·√2 / 2×5 - ( 2√5 / 2√2 + 5√2 / 5√5 )=
= 2√10/10+ 5√10 / 10 - ( √5·√2 / 2 + √2√5 / 5)= → aducem la acelasi numitor
= 7√10 / 10 - ( 5√10 / 10 + 2√10 /10 ) =
=7√10 / 10 - 7√10 /10=
= 0
