x²+10x+21=
a=1
b=10
c=21
d=b²-4ac
d=100-4×1×21⇒
100-84⇒
16⇒√d=√16⇒
d=4
x1x2=-b+-√d/2a
x1=-10+4/2⇒x1=-6/2⇒x1=-3
x2=-10-4/2⇒-14/2⇒x2=-7
b)x²+6x+5=
a=1
b=6
c=5
d=36-20⇒d=16⇒√d=√16⇒d=4
x1=-6-4/2⇒-10/2⇒x1=-5
x2=-6+4/2=-2/2⇒x2=-1
c)x²+10x+16
a=1
b=10
c=16
d=100-64⇒d=36⇒√d=√36⇒d=6
x1=-10-6/2⇒-16/2⇒x1=-8
x2=-10+6/2⇒-4/2⇒x2=-2
d)x²+13x+30=
a=1
b=13
c=30
d=169-120⇒d=49⇒√d=√49⇒d=7
x1=-13-7/2⇒-20/2⇒x1=-10
x2=-13+7/2⇒-6/2⇒x2=-3
e)t²-8t+7=
a=1
b=-8
c=7
d=64-28⇒d=36⇒√d=√36⇒d=6
t1=8+6/2⇒14/2⇒t1=7
t2=8-6/2⇒2/2⇒t2=1
f)t²-9t+18=
a=1
b=-9
c=18
d=81-72⇒d=9⇒√d=√9⇒d=3
t1=9+3/2⇒12/2⇒t1=6
t2=9-3/2⇒6/2⇒t2=3
g)t²-12t+27=
a=1
b=-12
c=27
d=144-108⇒d=36⇒√d=√36⇒d=6
t1=12+6/2⇒18/2⇒t1=9
t2=12-6/2⇒6/2⇒t2=3
h)t²-7t+10=
a=1
b=-7
c=10
d=49-40⇒d=9⇒√d=√9⇒d=3
t1=7+3/2⇒10/2⇒t1=5
t2=7-3/2⇒4/2⇒t2=2
i)a²-12a+20=
a=1
b=-12
c=20
d=144-40⇒d=4⇒√d=√4⇒d=2
a1=12+2/2⇒14/2⇒a1=7
a2=12-4/2⇒8/2⇒a2=4
nota d=delta
am facut direct calcul (-b)²
iar pt x1x2 direct calcul
ai la punctul a facut cu formule la restul am facut calculele pe foia mea si ti am rezultatul
succes
