x-y=1
x^2-2xy+4y=5
x=y+1
(y+1)^2-2y(y+1)+4y=5
y^2+2y+1-2y^2-2y+4y-5=0
y^2-4y+4=0
D=16-4*4=0
y=4/2=2
x=2+1=3
x-y=1
x^2-2xy+4y=5
x=y+1
(y+1)^2-2y(y+1)+4y=5
y^2+2y+1-2y^2-2y+4y-5=0
y^2-4y+4=0
D=16-4*4=0
y=4/2=2
x=2+1=3