bonjour
A = ( x + 3 + 2 x - 1) ( x + 3 - 2 x + 1)
= ( 3 x + 2) ( - x + 4)
B = ( ( 3 x - 1)² + ( 5 x + 6) ( 3 x - 1)
= ( 3 x - 1) ( 3 x - 1 + 5 x + 6)
= ( 3 x - 1 ) ( 8 x + 5)
c = ( 7 x - 1)² + 2 ( 7 x - 1)
= ( 7 x - 1) ( 7 x - 1 + 2)
= ( 7 x - 1) ( 7 x + 1)
D = ( 5 - x ) ( 2 x - 3 - 1 )
= ( 5 x - 3) ( 2x - 4)