Câu trả lời:
=\(x^4+2x^3+x^2+4x^2+4x-12\)
=\(x^4+2x^3+5x^2+4x-12\)
=\(x^4-x^3+3x^3-3x^2+8x^2+4x-12\)
=\(x^3(x-1)+3x^2(x-1)+4(2x^2+x-3)\)
=\(x^3(x-1)+3x^2(x-1)+4(2x^2-2x+3x-3)\)
=\(x^3(x-1)+3x^2(x-1)+4[2x(x-1)+3(x-1)]\)
=\(x^3(x-1)+3x^2(x-1)+4(x-1)(2x+3)\)
=\((x-1)[x^3+3x^2+4(2x+3)]\)
=\((x-1)(x^3+3x^2+8x+12)\)