`k) x^3 + x^2y + 3xy^2 + y^3`
`= ( x + y )^3`
`l) x^3 - 3x^2 + 3x - 1`
`= x^3 - 3.x^2 . 1 + 3 . x . 1^2 - 1^3`
`= ( x - 1 )^3`
`m) 8x^3 + 12x^2 + 6x + 1`
`= ( 2x )^3 + 3.(2x)^2 + 3 . 2x . 1^3`
`= ( 2x + 1 )^3`
`n) x^3 - 6x^2 + 12x - 8`
`= x^3 - 3.x^2 . 2 + 3.x.2^2 - 2^3`
`= ( x - 2 )^3`
`o) 8x^3 + 1`
`= ( 2x )^3 + 1^3`
`= ( 2x + 1 )( 4x^2 - 2x + 1 )`
`p) x^3 - 27`
`= x^3 - 3^3`
`= ( x - 3 )( x^2 + 3x + 9 )`
