Răspuns:
a) delta= b²-4ac
delta= 9-4×1×2
delta=1
x1=-b-rad delta/2a= 3-1/2=2/2=1
x2=-b+rad delta/2a=3+1/2=4/2=2
b)delta=b²-4ac
delta=49-4×1×12
delta=49-48= 1
x1= -b-rad delta/2a= 7-1/2=3
x2= -b+rad delta/2a= 7+1/2= 4
c)delta=b²-4ac
delta= 16-4×1×11
delta=16-44
delta=-28
x1= -b-rad delta/2a=> -4-rad 28/2
x2= -b+rad delta/2a=> -4+ rad 28/2
=> x>0 oricare ar fi x€R.
