a) x²+6x+9=0
a=1
b=6
c=9
Δ=b²-4ac
Δ=36-36
Δ=0
X= -b/2a
x=-6/2
x=-3
b) 49+x²+14x=0
a=1
b=14
c=49
Δ=196-196
Δ=0
x=-b/2a
x=-14/2
x=-7
c) x²+2.2x+1.21=0
a=1
b=2.2
c=1.21
Δ=4.84-4.84
Δ=0
x=-b/2a
x=-2.2/2
x=1.1
d) x²+8x+16=0
a=1
b=8
c=16
Δ=64-64
Δ=0
x=-b/2a
x=-8/2
x=-4
e) x²-4x+4
a=1
b=4
c=4
Δ=16-16
Δ=0
x=-b/2a
x=-4/2
x=-2