Réponse :
bonjour,
(x + 2)(x + 1) + (x + 2)(7x - 5)
= ( x+2 ) ( x+ 1 + 7x - 5 )
= ( x+ 2 ) ( 8x - 4 )
(x + 3) (3 - 2x) - (x + 3)(5 +x)
= ( x+3 ) ( 3-2x - ( 5 +x ) )
= ( x + 3 ) ( 3 - 2x - 5 -x )
= ( x + 3 ) ( - 3x - 2 )
(x - 6)(2 - x) - (2 - x)(3 - 4x)
=( 2 - x ) ( x - 6 -(3 - 4x ) )
=(2 - x ) ( x - 6 - 3 + 4x )
= ( 2 - x) ( 5x -9 )
voila :)
