bonjour,
A = ( x + 7) ( 2 x - 5 ) - ( 2 x - 5) ( 3 x + 2 )
A = ( 2 x - 5) ( x + 7 - 3 x - 2 )
A = ( 2 x - 5 ) ( - 2 x + 5 )
B = ( 4 x - 3) ( 2 x + 1 - 5 x )
B = ( 4 x - 3 ) ( - 3 x + 1 )
C = ( 2 x - 5) ( x + 2 - 3 x + 7 )
C = ( 2 x - 5 ) ( - 2 x + 9 )