(3x+2)^2-12x=9x^2+12x+4-12x=9x^2+4
(x-3)^2+3(2x+3)=x^2-6x+9+6x+9=x^2+18
Formule folosite:
(a+b)^2=a^2+2ab+b^2
(a-b)^2=a^2-2ab+b^2
