Răspuns:
2x^2-9(x-1)=(x-3)^2
2x^2-9x-9-x^2-2x*3+3^2=0
x^2-3x-9-3^2=0
x^2-3x=0
Delta=9
x12=-b+√Delta/2a=3+3/2=6/2=3
