bonjour
A = 18 x - 24 + 9 + 5 x
= 23 x - 13
B = - 6 x² + 2 x - 3 x + 1 - 5 x² + 2 x - 7
= - 11 x² + x - 6
C = 4 x² + 24 x + 36 + 3 x² - 8
= 7 x² + 24 x + 28
D = 49 x² - 81 - 10 x² + 15
= 39 x² - 66
A = ( x + 5 )²
B = ( x - 7 ) ( x + 7 )
C = ( 9 a + 2 )²
D = ( 8 - 4 x ) ( 8 + 4 x )
E = 8 x ( 3 x - x )