solve y^2-4y=13 using completing the square method

Answer 1

y^2-4y + (-4/2)^2=13+(-4/2)^2
y-4y+4=13+4
(y-2)^2-(sqrt(17))^2=0
(y-2-sqrt17)(y-2+sqrt17)=0
y= 2+sqrt17, y=2-sqrt17