Réponse :
Explications étape par étape
f(x) = ( x - 7 )² - 9
⇔ f(x) = ( x - 7 - 3 ) ( x - 7 + 3 )
⇔ f(x) = ( x - 10 ) ( x - 4 )
f(x) = 0
( x - 10 ) ( x - 4 ) = 0
x - 10 = 0 ou x - 4 = 0
⇔ x = 10 ⇔ x = 4
S = { 4 ,10 }
f(x) = 40
f(x) = ( x - 7 )² - 9
⇔ f(x) = x² - 14x + 49 - 9
⇔ f(x) = x² - 14x + 40
x² - 14x + 40 = 40
⇔ x² - 14x = 0
⇔ x ( x - 14 ) = 0
x = 0 ou x = 14
S = { 0, 14 }
