Réponse:
A=8-4(x-3)
=8-4x+1
= 20-4x
F=-x(2-x)+(x²-2x)-(3x²-4)
=-2x+x²+x²-2x-3x²+4
=-4x-x²+4
G=3x²-(x²-4x+5)-4x(x-3)
=3x²-x²+4x-5-4x²+12x
=-2x²+16x-5
H=(2x²-7x+4)-4x(-3+2x)
=2x²-7x+4+12x-8x²
=-6x²+5x+4
I=5x(-3x-6)-(-15x²+18x-6)
=-15x²-30x+15x²-18x+6
=-48x+6
