Bonjour;
A=
3x-8 -15x +8
= -12x
B=
7x-9 +14x² -28x
= 14x² -21x -9
C =
8x-9 - ( 36x² +20x -18x -10)
= 8x-9 - 36x² -20x + 18x +10
= -36x² +6x +1
D=
5x² -10 - 4x² +2x +2x -1
= x² +4x -11
E=
9x-7 -( 9x² -12x +4)
= 9x-7 - 9x² +12x -4
= -9x² +21x -11
F=
2x² +x -10x -5 -16x² -8x
= -14x² -17x -5
G=
-5x² -5x +81x² +18x +1
= 76x² +13x +1
H =
16x² -8x+1 -( x² +x -x-1)
= 16x² -8x+1 - x² -x +x+1
= 15x² -8x +2
