\(A=x^3-4x^2+4x+3x^2-12x+12\)
\(=x\left(x-2\right)^2+3\left(x-2\right)^2\)
\(=\left(x+3\right)\left(x-2\right)^2\)
\(B=x^3-10x^2+25x+x^2-10x+25\)
\(=x\left(x-5\right)^2+\left(x-5\right)^2\)
\(=\left(x+1\right)\left(x-5\right)^2\)
\(C=2x^3-2x^2-2x+x^2-x-1\)
\(=2x\left(x^2-x-1\right)+x^2-x-1\)
\(=\left(2x+1\right)\left(x^2-x-1\right)\)