-х^{2}+4х-3=0 2 x^{2} +4х=0 -2 x^{2} +4х+6=0
3)-x²+4x-3=0 2x²+4x=0 -2x²+4x+6=0 -2(x²-2x-3)=0 -2(-x²+x-3x-3)=0 -2(x(x+1)-3(x+1)=0 -2(x-3)(x+1)=0 (x-3)(x+1)=0 x-3=0 x+1=0 x=3 x=-1 x1=3;x2=-1