Bonjour,
On développe
(a-1)²-(4a-2)= (a-1)²-4a+2= a²-a-a+1-4a+2= a²-6a+3
on cherche le discriminant:
a= 1, b= -6 et c= 3
Δ= b²-4ac= (-6)²-4(1)(3)= 36-12 = 24 > 0
a1= (-(6-√24)/2(1)= (6-√(4x6))/2= (6-2√6)/2= 3-√6
a2= (6+2√6)/2= 3+√6
donc (a-3-√6)(a-3+√6)
sinon:
a²-6a+3= (a-3)²-6=(a-3-√6)(a-3+√6)
