Vous pouvais maider urgent Dm de maths

Bonjour , 
1/
f = 9 (-x+1)² - 4 (2x-3)²
f = 9 (1+x)² - 4 (2x-3)²
f = 9 ( 1² + x² + 2x ) - 4 ( (2x)² + 3² - 12x ) 
f = 9 + 9x² + 18x - 4 (4x² + 9 - 12x ) 
f = 9 + 9x² + 18x - 16x² - 36 + 48x
f = -7x² + 66x - 27
2/
f = 3² (-x+1) - 2² (2x-3)²
f = [ 3(-x+1) ]² - [ 2(2x-3) ]²
f = ( -3x+3)² - (4x-6 )²
3/
f = 9(-x+1)² - 4(2x-3)²
f = [ 9(-x+1) + 4(2x-3) ] [ 9(-x+1) - 4(2x-3) ]
f = [13(-x+1+2x-3) ] [ 5(-x+1-2x+3) ]
f = 13(x-2) 15(4-3x)