\(x^4+x^3+2x^2+x+1\)
\(=\left(x^4+x^3+x^2\right)+\left(x^2+x+1\right)\)
\(=x^2.\left(x^2+x+1\right)+\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^2+1\right)\)
\(x^4+x^3+2x^2+x+1=\left(x^4+x^2\right)+\left(x^3+x\right)+\left(x^2+1\right)\)
\(=x^2\left(x^2+1\right)+x\left(x^2+1\right)+\left(x^2+1\right)=\left(x^2+x+1\right)\left(x^2+1\right)\)
x4+x3+2x2+x+1
=(x4+2x2+1)+(x3+x)
=(x2+1)2+x(x2+1)
=(x2+1)(x2+1+x)