( a + b )² = a² + 2ab + b² , ( a – b )² = a² – 2ab + b² , a² – b² = ( a + b ) ( a – b ), ( a + b )³ = a³ + 3a² b + 3ab² + b³ , ( a – b )³ = a ³ – 3a² b + 3ab² – b³ , a³ + b³ = ( a + b )( a² – ab + b² ) , a³ – b³ = ( a – b )( a ² + ab + b² ) .
