Hãy giải bài toán này cho tôi

a) `(x+1)(x^2-x+1)`

`= (x+1) . (x^2 - x . 1 + 1^2)`

`= x^3 + 1^3`

`= x^3 + 1`

b) `(x-1)(x^2+x+1)`

`= (x-1) . (x^2 + x . 1 + 1^2)`

`= x^3 - 1^3`

`= x^3 - 1`

c) `(x-2) (x^2 + 2x+4)`

`= (x - 2) (x^2 + x . 2 + 2^2)`

`= x^3 - 2^3`

`= x^3 - 8`

d) `-4x + x^2 + 4`

`= x^2 - 2 . x . 2 + 2^2`

`= (x-2)^2`

e) `6x + 9 + x^2`

`= x^2 + 2 . x . 3 + 3^2`

`= (x+3)^2`