Verified answer

4x-4=(x-1)²

4x-4=(x-1)(x-1)

4x-4=x²-x-x+1

4x-4=x²-2x+1

4x-4-x²+2x-1=0

-x²+6x-5=0

D=36-4*(-1)*(-5)=36-20=16

x₁=(-6+4)/(-2)=1

x₂=(-6-4)/(-2)=5