Đáp án`+`Giải thích các bước giải:
` a. -x^3 + 3x^2 - 3x + 1`
`= -(x^3 - 3x^2 + 3x - 1)`
`= -(x - 1)^3`
` d . 8x^3 + 12x^2 + 6x + 1`
`= (2x)^3 + 4.(2x)^2 .1 + 3.2x.1^2 + 1^3 `
`= (2x + 1)^3`
` b . 8 - 12x + 6x^2 - x^3`
`= 2^3 - 3.2^2.x+ 3.2.x^2- x^3`
`= (2-x)^3`
` c . x^3 + x^2 + x/3 + x/27`
`= x^3 + 3.x^2.1/3 + 3.x.(1/3)^2 + (1/3)^3`
`= (x+1/3)^3`
` e. x^3 - 6x^2 y +12xy^2 - 8y^3`
`= x^3 - 3.x^2.2y + 3.x. (2y)^2 - (2y)^3`
`= (x-2y)^3`
` f . x^3 + 3/2 x^2 + 3/4 x + 1/8`
`= x^3 + 3.x^2 .1/2 + 3.x.(1/2)^2 + (1/2)^3`
`= (x+1/2)^3`
