Ta có: \(x^4+2002x^2+2001x+2002\)
\(=x^4+x^3-x^3+x^2-x^2+2002x^2+2002x-x+2002\)
\(=x^4+x^3+x^2-x^3-x^2-x+2002x^2+2002x+2002\)
\(=x^2\left(x^2+x+1\right)-x\left(x^2+x+1\right)+2002\left(x^2+x+1\right)\)
\(=\left(x^2-x+2002\right)\left(x^2+x+1\right)\)