delta=b^2-4ac
x1=(-b+radical din delta)/2a
x2=(-b-radical din delta)/2a
^=la puterea
*=inmultit
a)delta=16-12=4=2^2
x1=(4+2)/2=3
x2=(4-2)/3=2/3
b)delta=25-8=17
x1=(5+radical din 17)/2
x2=(5- radical din 17)/2
c)delta=25-16=9=3^2
x1=(5+3)/4=2
x2=(5-3)/4=1/4
d)delta=25+16=41
x1=(5+radical din 41)/-2
x2=(5-radical din 41)/-2
e)delta=9=3^2
x1=(3+3)/2=3
x2=(3-3)/2=0
f)delta=81=9^2
x1=(9+9)/2=9
x2=(9-9)/2=0
g)delta=36-36=0
x1=x2=6/2=3
h)delta=1-4=-3 => nu exista x1 si x2
