1) f(x) = x^2 -4x +3
f(x)=0 <=> x^2 -4x +3= 0
Delta=b2-4ac=(-4)^2 - 4(1x3)=4
X1=(4-2)/2=1
X2=(4+2)/2=3
Donc on a f(x)=(x-1)(x-3)
2)delta=16
X1= 2-4/-2=1
X2=2+4/-2=-3
f(x)=-1(x-1)(x+3)
3)delta=49
X1=-5-7/4=-3
X2=-5+7/4=1/2
4)delta=4-4=0
X=-2/2=-1
f(x)=(x+1)^2
5)delta =9
X1=-1-3/2 =-2
X2=-1+3/2 =1
f(x)=(x+2)(x-1)
