Réponse :
Bonjour,
A = 5x(3 – 6x) – 4
= 15x – 30x² – 4
= –30x² + 15 – 4
B = (3x – 2)(5 – 4x) – 3(7x – 2)
= 15x – 12x² – 10 + 8x – (21x – 6)
= 15x – 12x² – 10 + 8x – 21x + 6
= –12x² + 15x + 8x – 21x – 10 + 6
= –12x² + 2x – 4
C = 5x² – 4(3 – 7x)
= 5x² – (12 – 28x)
= 5x² – 12 + 28x
= 5x² + 28x – 12
D = 5(4x – 1) – (2x + 3)(–5x – 7)
= 20x – 5 – (–10x² – 14x – 15x – 21)
= 20x – 5 + 10x² + 14x + 15x + 21
= 10x² + 20x + 14x + 15x – 5 + 21
= 10x² + 49x + 16
