-5х^2+4х+1
D=16+20=36
x1=(-4-6)/(-10)=1 U x2=(-4+6)/(-10)=-0,2
-21х^2+х+2
D=1+168=169
x1=(-1-13)/(-42)=1/3 U x2=(-1+13)/(-42)=-2/7
-12х^2+7х-1
D=49-48=1
x1=(-7-1)/(-24)=1/3 U x2=(-7+1)/(-24)=1/4
27х^2-6х-1
D=36+108=144
x1=(6-12)/54=-1/9 U x2=(6+12)/54=1/3