\(x^4+2000x^2+1999x+2000\)
\(=\left(x^4-x\right)+\left(2000x^2+2000x+2000\right)\)
\(=x\left(x^3-1\right)+2000\left(x^2+x+1\right)\)
\(=x\left(x-1\right)\left(x^2+x+1\right)+2000\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left[x\left(x-1\right)+2000\right]\)
\(=\left(x^2+x+1\right)\left(x^2-x+2000\right)\)

