\(\left(x-1\right)^4-2\left(x^2-2x+1\right)^2+1\)
\(=\left[\left(x-1\right)^2\right]^2-2\left(x-1\right)^2+1^2\)
\(=\left[\left(x-1\right)^2-1\right]^2\)
\(\left(x-1\right)^4-2\left(x^2-2x+1\right)+1=\left[\left(x-1\right)^2\right]^2-2\left(x-1\right)^2+1^2\)
\(=\left[\left(x-1\right)^2-1\right]^2=\left[\left(x-1+1\right)\left(x-1-1\right)\right]^2\)
\(=\left[x\left(x-2\right)\right]^2\)