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(3a-1)(3a+1)-5(1-a)-5a

Răspuns :

(3a-1)²-5+5a-5a=(3a-1)²-5
Succes!!
[(3a) la a doua] - [1 la a doua] -5+5a-5a=
=9a patrat- 1-5=
9a patrat -6