bonjour
développer
(3a–1)²– 6a + 2 = (3a)² - 2*3a*1 + 1² - 6a + 2 =
= 9a ² -6a + 1 - 6a + 2
= 9a² -12a + 3
factoriser
(3a–1)²– 6a + 2 = (3a - 1)² - 2(3a - 1)
= (3a - 1)(3a - 1) - 2(3a - 1) [facteur commun (3a - 1) ]
= (3a - 1)(3a - 1 - 2)
= (3a - 1)(3a - 3) [ 3a - 3 = 3(a - 1) ]
= (3a - 1)*3*(a - 1)
= 3 (3a - 1)(a - 1)
s'il faut résoudre l'équation (3a–1)²–6a+2 = 0
3 (3a - 1)(a - 1) = 0 <=> (3a - 1)(a - 1) = 0
<=> 3a - 1 = 0 ou a - 1 = 0
a = 1/3 a = 1
S = {1/3 ; 1}
