\(x^5-5x^3+4x=x^5-4x^3-x^3+4x\)
\(=x^3\left(x^2-4\right)-x\left(x^2-4\right)\)
\(=\left(x^3-x\right)\left(x^2-4\right)\)
\(=x\left(x^2-1\right)\left(x-2\right)\left(x+2\right)\)
\(=x\left(x-1\right)\left(x+1\right)\left(x-2\right)\left(x+2\right)\)
\(x^5-5x^3+4x=x\left(x^4-5x^2+4\right)\)
\(=x\left(x^4-x^2-4x^2+4\right)=x\left[x^2\left(x^2-1\right)-4\left(x^2-1\right)\right]\)
\(=x\left(x^2-4\right)\left(x^2-1\right)\)
\(=x\left(x-2\right)\left(x+2\right)\left(x-1\right)\left(x+1\right)\)