bonjour
A= (7a+3)(6a-9)-(2a+5)(6a-9)
1) Développe A
A = 42 a² - 63 a + 18 a - 27 - ( 12 a² - 18 a + 30 a - 45 )
A = 42 a² - 45 a - 27 - 12 a² + 18 a - 30 a + 45
A = 30 a² - 57 a + 18
2) Factorise A
A = ( 6 a - 9 ) ( 7 a + 3 - 2 a - 5 )
A = ( 6 a - 9 ) ( 5 a - 2 )
