5( 2a - 1 )" - 2a + 1
= 5( 1 - 2a )" + ( 1 - 2a )
= ( 1 - 2a )( 5 - 10a + 1 )
= ( 1 - 2a )( 6 - 10a )
= 2( 3 - 5a )( 1 - 2a )
或者
= 5( 2a - 1 )" - ( 2a - 1 )
= ( 2a - 1 )( 10a - 5 - 1 )
= ( 2a - 1 )( 10a - 6 )
= 2( 5a - 3 )( 2a - 1 )