x^2+10x+9=0
delta=64 => x1=-1 x2=-9
5x^2+3x-2=0
delta =49 => x1=0,4 x2=-1
3x^2+5x-2=0
delta=49 => x1=0,33 x2=-2
x^2+2x+3=0
delta=-8 deci nu avem solutii
x^2-3√2x+4=0
delta=8 => x1=5√2/2 si x2=√2/2
x^2+4x-√3+1=0
delta=15+4√3 => x1=-4+radical din 16+4√3/2 si x2= -4- radical din 16+4√3/2