Réponse :
bonjour
A (x) = ( x + 2 )² - 9
1. A (x) = x² + 4 x + 4 - 9 = x² + 4 x - 5
2. A (x) = ( x + 2 - 3 ) ( x + 2 + 3 ) = ( x - 1 ) ( x + 5 )
3. A (3) = ( 3 + 2 )² - 9 = 5 ² - 9 = 25 - 9 = 16
A ( √3 - 2) = ( √3 - 2 + 2 )² - 9 = ( √3)² - 9 = 3 - 9 = - 6
4. A(x) = 0
( x - 1 ) ( x + 5 ) = 0
x = 1 ou - 5
5. x² + 4 x - 5 = - 5
x² + 4 x - 5 + 5 = 0
x ( x + 4 ) = 0
x = 0 ou - 4
Explications étape par étape :
