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a, 5x( x - 2 ) + 2( 2 - x )²
= 5x ( x - 2 ) + 2 ( x - 2 )²
= ( x - 2 ) [5x + 2( x - 2 )]
= ( x - 2 ) ( 5x + 2x - 4 )
= ( x - 2)(7x - 4)
b, (4x - 8 ) ( x² + 6 ) - (4x - 8 ) (x + 7 )
= (4x - 8 ) (x² + 6 - x - 7 )
= 4 ( x - 2 )(x² - x - 1 )
c, 7x ( y - 4 )² - ( 4 - y )³
= 7x ( 4 - y)² - ( 4 - y ) (4 - y)²
= (4 - y)² ( 7x - 4 + y)