Réponse :
Explications étape par étape
D=-2X²-{4X+(5-7X)-(2X²-5X+4)}
=-2X²-{4X+5-7X-2X²+5X-4}
= -2X²-4X-5X+7X+2X²-5+4
=-2X-1
E=-4X²-[-2X+X²]-[-[3X²-7)+4X}
= -4X²+2X-X²-[-3X²+7+4X]
=-4X²+2X-X²+3X²-7-4X
= -2X²-2X-7
F= -[-5X²+4X-(-2X+4X²)+7]
F= -{-5X²+4X+2X-4X²+7]
F=+5X²-4X-2X+4X²-7
=9X²-6X-7
G=3X²-{4X+5X²-[-2+7X)-(-3X+7)]
= 3X²-[4X+5X²+2-7X+3X-7]
=3X²-4X-5X²-2+7X-3X+7
=-2X²+7
