bonjour
A = ( 3 x - 2 )² - 9
1) A = 9 x² - 12 x + 4 - 9
A = 9 x² - 12 x - 5
2 ) A = ( 3 x - 2 - 3 ) ( 3 x - 2 + 3 )
A = ( 3 x - 5 ) ( 3 x + 1 )
a) 9 ( √2)² - 12 √2 - 5 = 18 - 12 √2 - 5 = 13 - 12 √2
b ) A = 0
( 3 x - 5 ) ( 3 x + 1 ) = 0
l'un des facteurs est nul donc x = 5/3 ou - 1/3
c) A = 16
( 3 x - 2 )² - 9 = 16
( 3 x - 2 )² - 9 - 16 = 0
( 3 x - 2)² - 25 = 0
( 3 x - 2 - 5 ) ( 3 x - 2 + 5 ) = 0
( 3 x - 7 ) ( 3 x + 3 ) = 0
x = 7/3 ou - 1
