Ta có : \(x^5+2x^4+3x^3+3x^2+2x+1\)
\(=x^5+x^4+x^4+x^3+2x^3+x^2+2x^2+x+x+1\)
\(=\left(1+x\right)+\left(x+x^2\right)+\left(2x^2+2x^3\right)+\left(x^3+x^4\right)+\left(x^4+x^5\right)\)
\(=\left(1+x\right)+x\left(1+x\right)+2x^2\left(1+x\right)+x^3\left(1+x\right)+x^4\left(1+x\right)\)
\(=\left(x+1\right)\left(1+x+2x^2+x^3+x^4\right)\)
Chúc bạn học tốt!