\(=x^3\left(x-2\right)+10x\left(x-2\right)=x\left(x-2\right)\left(x^2+10\right)\)
\(x^4-2x^3+10x^2-20x\)
\(=x\left(x^3-2x^2+10x-20\right)\)
\(=x\left[x^2\left(x-2\right)+10\left(x-2\right)\right]\)
\(=x\left(x-2\right)\left(x+10\right)\)
\(=x^3\left(x-2\right)+10x\left(x-2\right)\\ =\left(x^3-10x\right)\left(x-2\right)\\ =x\left(x-10\right)\left(x-2\right)\)
`x^4 - 2x^3 + 10x^2 - 20x = 0`
`-> x(x-2)(x^2+10) = 0`
`-> x = 0` hoặc `2`
\(=x^3\left(x-2\right)+10x\left(x-2\right)=x\left(x-2\right)\left(x^2+10\right)\)
