\(x^{11}+x^{10}+x^9+x^8+x^7+x^6+x^5+x^4+x^3+x^2+x+1\)

\(=x^{10}\left(x+1\right)+x^8\left(x+1\right)+x^6\left(x+1\right)+x^4\left(x+1\right)+x^2\left(x+1\right)+\left(x+1\right)\)

\(=\left(x+1\right)\left(x^{10}+x^8+x^6+x^4+x^2+1\right)\)

\(=\left(x+1\right).\left[x^8.\left(x^2+1\right)+x^4.\left(x^2+1\right)+\left(x^2+1\right)\right]\)

\(=\left(x+1\right).\left(x^2+1\right).\left(x^8+x^4+1\right)\)

Chúc bạn học tốt!!!