bonjour
f (x) = x² - 6 x + 8
( x - 2 ) ( x - 4 ) = x² - 4 x - 2 x + 8 = x² - 6 x + 8
( x - 3 )² - 1 = x² - 6 x + 9 - 1 = x² - 6 x + 8
f (1) = 2 - 6 + 8 = 4
f ( x) = 0
( x - 2 ) ( x - 4 ) = 0 donc x = 2 ou 4
x² - 6 x + 8 = 8
x² - 6 x + 8 - 8 = 0
x² - 6 x = 0
x ( x - 6 )= 0
x = 0 ou 6
( x - 3 )² - 1 = 3
( x - 3 )² - 1 - 3 = 0
( x - 3 )² - 4 = 0
( x - 3 - 2 ) ( x - 3 + 2 ) = 0
( x - 5 ) ( x - 1 ) = 0
x = 5 ou 1
