Đáp án:
`48, m^3 + 27`
`= m^3 + 3^3`
`= (m + 3)(m^2 - m.3 + 3^2)`
`= (m + 3)(m^2 -3m + 9)`
`49, x^3 + 8 = x^3 + 2^3`
`= (x + 2)(x^2 -x.2 + 2^2)`
`= (x + 2)(x^2 - 2x + 4)`
`50, 1/27 + a^3 = (1/3)^3 + a^3`
`= (1/3 + a)[(1/3)^2 - 1/3 . a + a^2]`
`= (1/3 + a)(1/9 - 1/3 a + a^2)`
`51, 8x^3 + 27y^3 = (2x)^3 + (3y)^3`
`= (2x + 3y)[(2x)^2 -2x.3y + (3y)^2]`
`= (2x + 3y)(4x^2 - 6xy + 9y^2)`
`52, 1/8 x^3 + 8y^3 = (1/2 x)^3 + (2y)^3`
`= (1/2 x + 2y)[(1/2 x)^2 - 1/2x . 2y + (2y)^2]`
`= (1/2 x + 2y)(1/4 x^2 - xy + 4y^2)`
`53, 8x^6 - 27y^3 = (2x^2)^3 - (3y)^3`
`= (2x^2 - 3y)[(2x^2)^2 + 2x^2 . 3y + (3y)^2]`
`= (2x^2 - 3y)(4x^4 + 6x^2 y + 9y^2)`
`54, 1/8 x^3 - 8 = (1/2 x)^3 - 2^2`
`= (1/2 x - 2)[(1/2 x)^2 + 1/2 x . 2 + 2^2]`
`= (1/2 x - 2)(1/4 x^2 + x + 4)`
`55, 1/64 x^6 - 125 y^3 = (1/4 x^2)^3 - (5y)^3`
`= (1/4 x^2 - 5y)[(1/4 x^2)^2 + 1/4 x^2 . 5y + (5y)^2]`
`= (1/4 x^2 - 5y)(1/16 x^4 + 5/4 x^2 y + 25y^2)`
`56, (a + b)^3 - c^3`
`= (a + b - c)[(a + b)^2 + (a + b)c + c^2]`
`= (a + b - c)(a^2 + 2ab + b^2 + ac + bc + c^2)`
`57, x^3 - (y - 1)^3`
`= [x - (y - 1)][x^2 + x(y - 1) + (y - 1)^2]`
`= (x - y + 1)(x^2 + xy - x + y^2 - 2y + 1)`
`58, 125 - (x + 2)^3`
`= 5^3 - (x + 2)^3`
`= [5 - (x + 2)][5^2 + 5(x + 2) + (x + 2)^2]`
`= (5 - x - 2)(25 + 5x + 10 + x^2 + 2.x.2 + 2^2)`
`= (3 - x)(25 + 5x + 10 + x^2 + 4x + 4)`
`= (3 - x)(x^2 + 9x + 39)`
`59, (x + 3)^3 - 8`
`= (x + 3 - 8)[(x + 3)^2 + (x + 3).8 + 8^2]`
`= (x - 5)(x^2 + 2.x.3 + 3^2 + 8x + 24 + 64)`
`= (x - 5)(x^2 + 6x + 9 + 8x + 24 + 64)`
`= (x - 5)(x^2 + 14x + 97)`
