( 2 - x ) - ( 4 - x² ) = ( 2 - x ) - ( 2 - x )( 2 + x ) = ( 2 - x )( 1 - ( 2 + x )) =
= ( 2 - x )( 1 - 2 - x ) = ( 2 - x )( - 1 - x )
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( a² - 4 ) + ( a - 2 )² = ( a - 2 )( a + 2 ) + ( a - 2 )² = ( a - 2 )( ( a + 2 ) - ( a - 2 )) =
= ( a - 2 )( a + 2 - a + 2 ) = 4( a - 2 )