Réponse :
bonjour
A (x) = 9 x² - ( 2 x - 3 )²
A (x) = 9 x² - ( 4 x² - 12 x + 9)
A (x) = 9 x² - 4 x² + 12 x - 9
A (x) = 5 x² + 12 x - 9
A ( x) = (3 x + 2 x - 3 ) ( 3 x - 2 x + 3 )
A (x) = ( 5 x - 3 ) ( x + 3 )
A (x) = 9
5 x² + 12 x - 9 = - 9
5 x² + 12 x - 9 + 9 = 0
5 x² + 12 x = 0
x ( 5 x + 12 ) = 0
x = 0 ou - 12/5
A (√2) = ( 5 √2 - 3 ) ( √2 + 3 )
A ( √2 ) = 10 + 15 √2 - 3 √2 - 9 = 12 √2 + 1
A ( -3) = ( - 15 - 3 ) ( - 3 + 3 ) = 0
Explications étape par étape
