Bonjour ,
A = 18x² + 24x + 8
A = (√18)x² + (2 × (√18) x × √8) + √8
A = (√18 x + √8 ) ²
B = 25 + 49x² - 35x
B = 5² + (7x)² - 2 × 7x × 5
B = (5 - 7x)²
C = 16x² - 4
C = (4x)² - 2²
C = (4x+2) ( 4x-2)
D = (3x+4)² - 36
D = (3x+4)² - 6²
D = [ (3x+4) - 6 ] [ 3x+4) + 6 ]
D = ( 3x - 2 ) ( 3x + 10 )
E = (2x+5)² - (3x+7)²
E = [ (2x+5) + (3x+7) ] [ (2x+5) - (3x+7) ]
E = [ 2x+5 +3x+7 ] [ 2x+5 - 3x - 7 ]
E = ( 5x +12 ) ( -x - 2 )
Voilà : )