Quelqu'un peu m'aider pour lexercice 2 svp :)?

Bonjour
F = (4x-3)(3x+4)-(4x-3)(4-5x) = (4x-3)[(3x+4)-(4-5x)] = (4x-3)(3x+4-4+5x) =
(4x-3)(8x) = 8x(4x-3)
G = (3x-1)(x+6)+(3x-1)² = (3x-1)[(x+6)+(3x-1)] = (3x-1)(x+6+3x-1) = 
(3x-1)(4x+5)
H = 49x²+42x+9 = (7x)²+2(7)(3)+3² = (7x+3)²
I = 81 - 4x² = (9+2x)(9-2x)
J = (3x+1)²-9 = [(3x+1)+3][(3x+1)-3] = (3x+4)(3x-2)
K = (4x+3)² - (2+3x)² = [(4x+3)+(2+3x)][(4x+3)-(2+3x)] = (7x+5)(x+1)