6x^2+7x=5 x(x-5)=1-4x
D=49+4*6*5=169 X1=(-7+13)/12=0,5 X2=(-7-13)/12=20/12=1 2/3 X^2-5x-1+4x=0 X^2-x-1=0 D=1+4*1*2=9 X1=(5+3)/4=2 X2=(5-3)/4=0,5