Factorise : (a + b)3- a - b
(a + b)3 - a - b = ( a + b )3 - ( a + b ) = ( a + b )[ ( a + b )2 - 1 ] = ( a + b )[ ( a + b )2 - (1)2 ] = ( a + b )[( a + b ) + 1 ][( a + b ) - 1] [ a2 - b2 = ( a + b )( a - b )] = ( a + b )( a + b + 1 )( a + b - 1 )
