d) \(x^5+x-1\)
\(=x^5-x^2+x^2+x-1\)
\(=\left(x^5-x^2\right)+\left(x^2+x-1\right)\)
\(=x^2.\left(x^3-1\right)+\left(x^2+x-1\right)\)
\(=x^2.\left(x-1\right).\left(x^2+x-1\right)+\left(x^2+x-1\right)\)
\(=\left[x^2.\left(x-1\right)-1\right].\left(x^2+x-1\right)\)
\(=\left(x^3-x^2-1\right).\left(x^2+x-1\right)\)
Chúc bạn học tốt!