\(a,1-y^3+6xy^2-12x^2y+8x^3=1-\left(y^3-6xy^2+12x^2y-8x^3\right)=1^3-\left(y-2x\right)^3=\left(1-y+2x\right)\left[1+1.\left(y-2x\right)+\left(y-2x\right)^2\right]=\left(1-y+2x\right)\left(1+y-2x+y^2-4x+4x^2\right)=\left(1-y+2x\right)\left(1+y-6x+y^2+4x^2\right)\)\(b,\left(x-z\right)^2-y^2+2y-1=\left(x-z\right)^2-\left(y^2-2x+1\right)=\left(x-z\right)^2-\left(y-1\right)^2=\left(x-z+y-1\right)\left(x-z-y+1\right)\)\(c,x^3+y^3+3y^2+3y+1=x^3+\left(y+1\right)^3=\left(x+y+1\right)\left[x^2-x\left(y+1\right)+\left(y+1\right)^2\right]\left(x+y+1\right)\left(x^2-xy-x+y^2+2y+1\right)\)