y^2+(y-42)/y^2-36
y^2+y-42=0
D=1+168=169=13^2
x1=-1+13/2=6
x2=-1-13/2=-7
(y-6)(y+7)/(y-6)(y+6)=y+7/y+6
y^2+(y-42)/y^2-36
y^2+y-42=0
D=1+168=169=13^2
x1=-1+13/2=6
x2=-1-13/2=-7
(y-6)(y+7)/(y-6)(y+6)=y+7/y+6