Bonjour,
A= -4x+(3x+1)(-2x+8)
= -4x+(-6x²+24x-2x+8)
= -6x²+18x+8
B= 6+(8x-1)(7-2x)-5x²
= 6+(56x-16x²-7+2x)-5x²
= -21x²+58x-1
C =(5x+7)(3x-8)-(-5x-2)+10(x²-4)
=15x²-40x+21x-56+5x+2+10x²-40
= 25x²-14x-94
D= -6x(-3x+7)-(3+2x)(-4x+1)+(6x-9)
= 18x²-42x-(-12x+3-8x²+2x)+6x-9
= 18x²-42x+12x-3+8x²-2x+6x-9
= 26x²-26x-12
