Aider moi svp c'est urgent

bonsoir

a = 15 x² - 35 x - 18 x + 42 - ( 25 x² - 36)
a = 15 x² - 53 x + 42 - 25 x² + 36
a = - 10 x² - 53 x + 78

b = 9 x² - 81 + 49 x² + 28 x + 4
b = 58 x² + 28 x - 77

c =  16 x² - 24 x + 9 - ( 4 x² - 4 x + 1)
c = 16 x² - 24 x + 9 - 4 x² + 4 x - 1
c = 12 x² - 20 x + 8

d = (3 x + 8) ( 3 x + 8 - 6 x + 7)
d = ( 3 x + 8) ( - 3 x + 15)

e = ( 8 x - 4 + 2 x - 3) ( 8 x - 4 - 2 x + 3)
e = ( 10 x - 7) ( 6 x - 1)

Bonsoir , 
* Développement : 
A = (5x-6) (3x-7) - (5x-6) (5x+6)
A = 15x² - 35x - 18x + 42 - [ ( 5x)² - 6² ]
A = 15x² - 53x + 42 - 25x² + 36 
A = -10x² - 53x + 78 
B = 9x(x-9) + (7x+2)²
B = 9x² - 81 + (7x)² + 2² + 28x
B = 9x² - 81 + 49x² + 4 + 28x
B = 58x² +28x - 77
C = (4x-3)² - (2x-1)²
C = (4x)² + 3² - 24x - [ (2x)² + 1² - 4x ]
C = 16x² + 9 - 24x - 4x² - 1 + 4x 
C = 12x² - 20x + 8 
* Factorisation : 
D = (3x+8)² - (6x-7) (3x+8)
D = (3x+8) [ (3x+8) - (6x-7) ]
D = (3x+8) [ 3x+8-6x+7 ]
D = (3x+8) (15-3x)
E = (8x-4)² - (2x-3)²
E = [ (8x-4) + (2x-3) ] [ (8x-4) - (2x-3) ]
E = [ 8x-4+2x-3 ] [ 8x-4-2x+3 ]
E = (10x-7) (6x-1)