Quelqu'un peut m'aider? Merci d'avance​

bonjour

f (x) = ( x + 2 )² - 9

f ( x) =  x² + 4 x + 4 - 9 =  x² + 4 x - 5

f ( x) = ( x + 2 - 3 ) ( x + 2 + 3 )

 = ( x - 1 ) ( x + 5 )

f (x) = - 9

( x + 2 )² - 9 = -  9

( x + 2 )² - 9 + 9 = 0

( x + 2 )² = 0

x =  - 2

f ( x) = 0

( x - 1 ) ( x + 5 ) = 0

x = 1 ou - 5

f ( x ) = - 5

( x + 2 )² - 9 = - 5

( x + 2 )² - 9 + 5 = 0

( x + 2 )² - 4 = 0

( x + 2 - 2 ) ( x + 2 + 2 ) = 0

x ( x + 4 ) = 0

x =  0 ou - 4

bjr

f(x) = (x+2)² - 9

f(x) = x² + 4x + 4 - 9 = x² + 4x - 5

f(x ) = (x+2)² - 9

= (x+2-3)(x+2+3) = ( x - 1 ) ( x + 5 )

f(x) = -9

tu remplaces f(x) par sa valeur

(x+2)² - 9 = -9

(x + 2)² - 9 + 9 = 0

(x+2)² = 0

x = -2

f(x) = 0

(x+2)² - 9 = 0

(x-1)(x+5)= 0

x = 1 ou x = -5

f(x) = - 5

(x+2)² - 9 + 5 = 0

(x+2)² - 4 = 0

(x+2+2)(x+2-2) = 0

(x+4) ( x ) = 0

x = -4 ou x = 0

bonne journée