Răspunsuri

2014-11-16T17:41:35+02:00
(a/b+b/a)^2 = (a/b)^2 + 2*a/b*b/a + (b/a)^2 = (a/b)^2 + 2 + (b/a)^2
(a/b - b-a)^2 = (a/b)^2 - 2 * a/b * b/2 + (b/a^2) = (a/b)^2 -2 + (a/b)^2
(a/b+b/a)^2 + (a/b-b/a)^2 = 2[(a/b)^2 + (b/a)^2] +2-2 =2[(a/b)^2 + (b/a)^2] 
Dar 2 apartine N , (a/b)^2 e modul din a^2/b^2 ce apartine N , (b/a)^2 e modul din b^2/a^2 deci apartine N . => Relatia apartine multimii N
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