Vũ Thanh Bình sai rùi
\(x^5+5x^3+4x\)
\(=x^5+4x^3+x^3+4x\)
\(=x^3.\left(x^2+4\right)+x\left(x^2+4\right)\)
\(=\left(x^3+x\right)\left(x^2+4\right)\)
\(=x\left(x^2+1\right)\left(x^2+4\right)\)
\(=x^5+4x^3+x^3+4x\)
\(=x^3\left(x^2+4\right)+x\left(x^2-4\right)\)
\(=\left(x^3+x\right)\left(x^2-2^2\right)\)
\(=x\left(x^2+1\right)\left(x-2\right)\left(x+2\right)\)
\(x^5+5x^3+4x\)
\(=x^5+x^3+4x^3+4x\)
\(=x^3\left(x^2+4\right)+x\left(x^2+4\right)\)
\(=\left(x^2+4\right)\left(x^3+x\right)\)
\(=x\left(x^2+1\right)\left(x^2+4\right)\)
