Réponse :
bonjour,
C + D
= ( -3x + 1 ) + (x -2 )
= -3x + 1 + x - 2
= -2x - 1
-5×C
= -5 × ( - 3x + 1 )
= 15x -5
D×10
= 10 × ( x - 2 )
= 10x -20
C ×D
= ( -3x + 1 ) × (x -2 )
= -3x × x - 3x ×(-2) + x ×1 - 2 × 1
= -3x² +6x + x - 2
= -3x² + 7x - 2
voila:)
