Đáp án `+` Giải thích các bước giải:
` a , (x-3)(x^2 + 3x + 9) `
` = (x-3)(x^2 + 3.x + 3^2) `
`= x^3 - 3^3 `
`=x^3 - 27`
` b , (x^2 + 3)(x^4 - 3x^2 + 9) `
`= (x^2 + 3)[(x^2)^2 - x62 .3 + 3^2] `
`= (x^2)^3 + 3^3 `
`= x^6 + 27`
` c , (x+2)(x^2 - 2x + 4)`
`= (x+2)(x^2 -x.2 + 2^2) `
`= x^3 + 2^3`
`=x^3 + 8`
` d , (2x+1)(4x^2 - 2x + 1) `
` (2x+1)[(2x)^2 - 2x . 1 + 1^2] `
`= (2x)^3 + 1^3 `
`= 8x^3 + 1`
` e , (x-4)(x^2 + 4x + 16) `
`= (x-4)(x^2 + x.4 + 4^2) `
`= x^3 - 4^3`
`= x^3 - 64`
` f, (x^2 + 2)(x^4 - 2x^2 + 4)`
`=(x^2 + 2)[(x^2)^2 - x^2 . 2 + 2^2] `
`= (x^2)^3 + 2^3 `
`= x^6 + 8 `
` g , (x-5)(x^2 + 5x + 25) `
`= (x-5)(x^2 + x.5 + 5^2)`
`= x^3 - 5^3 `
` = x^3 - 125`
` h , (3x+2)(9x^2 - 6x + 4)`
`= (3x+2)[(3x)^2 - 3x.2 + 2^2] `
`= (3x)^3 + 2^3`
`= 27x^3 + 8 `
