bonjour

f (x) = ( x + 2 )² - 9

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

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

3.  f (x) = - 9

( x + 2 )² - 9 = - 9

( x + 2 )² = 0

x = - 2

4. f (x) = 0

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

x = - 5 ou 1

5. f (x) = - 5

x² + 4 x - 5 = - 5

x² + 4 x =  0

x ( x + 4 ) = 0

x = 0 ou - 4