a) x²+6x+9=0?

Δ=b²-4ac

Δ=6²-4*1*9

Δ=36-36

Δ=0

baskaras

x= -b+/-√Δ sobre 2a

x¹= -6÷2= -3

x²= -6÷2= -3

b)x²+x+12=0

Δ=b²-4ac

Δ=1²-4*1*12

Δ=1-48

Δ= -47

c)7x²+x+1=0

Δ=b²-4ac

Δ=1²-4*7*1

Δ=1-28

Δ=-27

d)x²-x-1=0

Δ=b²-4ac

Δ=(-1²）-4*1*(-1

Δ=1+4

Δ=5