Đáp án:
`x^4 + 3x^3 + 3x^2 + 3x + 2`
`= x^4 + 2x^3 + x^3 + 2x^2 + x^2 + 2x + x + 2`
`= (x^4 + 2x^3) + (x^3 + 2x^2) + (x^2 + 2x) + (x + 2)`
`= x^3(x + 2) + x^2 (x + 2) + x(x + 2) + (x + 2)`
`= (x + 2)(x^3 + x^2 + x + 1)`
`= (x + 2)[(x^3 + x^2) + (x + 1)]`
`= (x + 2)[x^2 (x + 1) + (x + 1)]`
`= (x + 2)(x + 1)(x^2 + 1)`