Vous pouvez m'aider à l'exercice 3,5 et 6 Svp ? Merci!

Ex 3
A= (4x-8)-(3x-7)+(-2x+3)
A= 4x-8-3x+7-2x+3
A= -x +2
B= (6x²-5x+7)-(4x²-5x-5)
B= 6x²-5x+7-4x²+5x+5
B=2x²+12
C= -(3x²-5x+2)+(2x²-2x+8)-(3-2x+2x²)
C= -3x²+5x-2 + 2x²-2x+8 -3+2x-2x²
C= -3x² +5 x +3
Ex 5
A= (6x-4)-(2x-8)
A= 6x-4-2x+8
A= 4x +4

B=(6x-4)(2x-8)
B= 12x²-48x -8x +32
B= 12x²-56x+32

C= (6x-4)+(2x-8)
C= 6x-4+2x-8
C= 8x-12

D=6x-4(2x-8)
D= 6x -8x + 32
D= -2x+32

Exercice 6
A= (x-5)(3x+5)+(4x-2)(5x-2)
A= 3x² +5x -15x-25 + 20x²-8x-10x+4
A= 23x²-28x -21

B=(3x+2)(2x-5)-(6x-5)(4x+2)
B= 6x² -15x +4x -10 -(24x²+12x-20x-10)
B= 6x²-15 x +4x-10 - 24x²-12x +20x+10
B= -18x²-3x

C=(4x-5)(2x-5)-(4x+1)(2x-3)
C= 8x²-20x-10x +25 -(8x²-12x+2x-3)
C= 8x²-20x-10x+25-8x²+12x-2x+3
C=-20x +28