Đáp án`+`Giải thích các bước giải:

` 7) `

` 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 ) `

` 8) `

` ( x + 4 )^3 - 64 `

` = ( x + 4 - 4 )[ ( x + 4 )^2 + 4( x + 4 ) + 4^2 ] `

` = x( x^2 + 4x + 4 + 4x + 16 + 16 ) `

` = x( x^2 + 8x + 36 ) `

`9) `

` x^6 - 1 `

` = ( x^2 - 1 )( x^4 + x^2 + 1 ) `

` = ( x + 1 )( x - 1 )( x^4 + x^2 + 1 ) `

` 10) `

` mx + my + m `

` = m( x + y + 1 ) `

` 11) `

` m( a - b ) - m^2 ( a - b ) `

` = ( a - b )( m - m^2 ) `

` = m( a - b )( 1 - m ) `

` 12) `

` 2( x - y ) - a( x - y ) `

` = ( x - y )( 2 - a ) `

` 13) `

` a^2b - 2ab^2 + ab `

` = ab( a - 2b + 1 ) `

` 14) `

` -3x^2y^3 + bx^3y^2 - x^2y^2 `

` = x^2y^2 ( -3y + bx - 1 ) `

` 15) `

` 2( x - y ) + ( y - x ) `

` = 2( x  -y ) - ( x - y ) `

` = ( x - y )( 2 - 1 ) `

` = x - y `