Có thể chi tiết ra ko bạn, mình cảm ơn.
\(x^4+2x^3+5x^2+4x-12\)
\(=\left(x^4+2x^3+x^2\right)+4x^2+4x-12\)
\(=\left(x^2+x\right)^2+4\left(x^2+x\right)-12\)
\(=\left(x^2+x\right)^2-2\left(x^2+x\right)+6\left(x^2+x\right)-12\)
\(=\left(x^2+x\right)\left(x^2+x-2\right)+2\left(x^2+x-2\right)\)
\(=\left(x^2+x+2\right)\left(x^2+x-2\right)\)
\(=\left(x^2+x+2\right)\left(x^2-x+2x-2\right)\)
\(=\left(x^2+x+2\right)\left[x\left(x-1\right)+2\left(x-1\right)\right]\)
\(=\left(x-1\right)\left(x+2\right)\left(x^2+x+2\right)\)