my^2+2y-4=0
-4(y^-2)+2(y^-1)+m=0
4(y^-2)-2(y^-1)-m=0
4(y^-2)-2(y^-1)=m
(2(y^-1)-0.5)=4(y^-2)-2(y^-1)-m
(2(y^-1)-0.5)=0
m=-0.25
y=4
That's what you meant by one root, right?
