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Aflati numarul natural n stiind ca:
(4-n)×(5-n)=12


Răspuns :

Răspuns:

(4-n)×(5-n) = 12.

Desfacem parantezele:

20-4n-5n+n^2 =12

n^2 - 9n +20 =12 /-12

n^2 -9n +8 =0

delta = 81-32 = 49

n1 = (9+7)/2 = 8

n2 = (9-7)/2 = 1