` \color{#0074D9}{#n}\color{#0088DD}{q}\color{#3399FF}{o}\color{#66AAFF}{c}\color{#99CCFF}{c} `

`52) (x+2)^3 - 27 `

`= (x+2)^3 - 3^3 `

`= [(x+2) - 3][(x+2)^2 + (x+2) . 3 + 3^2] `

`= (x+2-3)(x^2 + 4x + 4 + 3x + 6 + 9) `

`= (x-1)(x^2 + 7x + 19) `

`***` HĐT `: a^3 - b^3 = (a-b)(a^2 + ab + b^2) `

`53) (a+3b)^2 - 9b^2 `

`= (a+3b)^2 - (3b)^2 `

`= [(a+3b) - 3b][(a+3b) + 3b] `

`= (a+3b-3b)(a+3b+3b) `

`= a(a+6b) `

`***` HĐT `: a^2 - b^2 = (a-b)(a+b)`

`54) 9x^6 - 12x^7 + 4x^8 `

`= x^6(9 - 12x + 4x^2) `

`= x^6(4x^2 - 12x + 9) `

`= x^6[(2x)^2 - 2 . 2x . 3 + 3^2] `

`= x^6(2x-3)^2 `

`***` HĐT `: (a-b)^2 = a^2 - 2ab + b^2 `

`55) x^3 + 6x^2 + 12x + 8 `

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

`= (x+2)^3 `

`***` HĐT `: (a+b)^3 = a^3 + 3a^2b + 3ab^2 + b^2 `

`56) (a-5b)^2 - 16b^2 `

`= (a-5b)^2 - (4b)^2 `

`= [(a-5b) - 4b][(a-5b) + 4b] `

`= (a-5b-4b)(a-5b+4b) `

`= (a-9b)(a-b)`

`***` HĐT `: (a-b)^2 = a^2 - 2ab + b^2 `

`57) m^3 + 27 `

`= m^3 + 3^3 `

`= (m+3)(m^2 - 3m + 9) `

`***` HĐT `: a^3 + b^3 = (a+b)(a^2 - ab + b^2) `

`58) x^3 + 3x^2 + 3x + 1 `

`= x^3 + 3 . x^2 . 1 + 3 . x . 1^2 + 1^3 `

`= (x+1)^3 `

`***` HĐT `: (a+b)^3 = a^3 + 3a^2b + 3ab^2 + b^3 `

`59) x^3 + 8 `

`= x^3 + 2^3 `

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

`= (x+2)(x^2 + 2x + 4) `

`***` HĐT `: a^3 + b^3 = (a+b)(a^2 - ab + b^2) `

`60) m^3 - 3m^2 + 3m - 1 `

`= m^3 - 3 . m^2 . 1 + 3 . m . 1^2 + 1^3 `

`= (m-1)^3 `

`***` HĐT `: (a-b)^3 = a^3 - 3a^2b + 3ab^2 + b^3 `

`61) m^3 - 6m^2 + 12m - 8 `

`= m^3 - 3 . m^2 . 2 + 3 . m . 2^2 - 2^3 `

`= (m-2)^3 `

`***` HĐT `: (a-b)^3 = a^3 - 3a^2b + 3ab^2 + b^3 `