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Determinati nr.intreg x,stiind ca x(x-2)=15

Răspuns :

(1) x·(x-2) = 15 => x·(x-2) = 5·3 => x·(x-2) = 5·(5-2) => x = 5
(2) x·(x-2) = 15 => x·(x-2) = (-3)·(-5) => (-3)·(-3-2) => x = -3

=> x ∈ {-3,5}