3x²-9x+4x +12= 0
3x(x-3) + 4(x-3)=0
(x-3)(3x+4) =0
atunci x-3= 0 x=3
3x=-4 x=-4/3
2x²-2x-x +1 = 0
2x(x-1) -1(x-1)=0
(x-1)(2x-1)=0
x=1
2x=1 x=1/2
(x-3)²=0
x-3=0
x=3
