Solve by completing the square Please show all steps and exp

Solve by completing the square. Please show all steps and explain. The answer is y=1,3

Solve by completing the square. Please show all steps and explain. The answer is y = 1, 3 y^2 - 4y + 3 = 0

y^2 - 4y + 3 =0

y^2 -4y = -3

we have formula : (a+b)^2 = a^2 +b^2 +2ab

we have a = 1; 2ab = -4

b = -2

y^2 - 4y +4 -4 = -3

y^2 - 4y + -4 = -3

(y -2)^2 = 1

(y -2)^ = 1

y-2 = +/- 1

y = 2+1

y = 3

y = 2-1

y = 1

Solution : y = 1 ,3