1)Resolva as equações do 2º grau: a) x² – 3x – 4 = 0 (R: -1, 4...

1) x2 - 5x + 6=0

a=1 ∆=b²-4.a.c x=-b+-√∆/2a

B=-5 ∆=25-4.1.6 x=5 + - √1/2

c=6 ∆=25-24 x=5+ - 1/2

∆= 1 x1=5+1/2

x1=6/2 x1= 3

x2=5-1/2

x2=4/2 x2=2

2)

a=1 ∆= b²-4.a.c x=-b + - √∆/2a

B= -8 ∆= 64-48 x=8+-√16/2.1

c=12 ∆= 16 x= 8+-4/2

x1=8+4/2 x1=12/2

x1= 6

x2=8-4/2 x2=4/2=2

3)

a=1 ∆=b² -4.a.c x= -b +-√∆/2a

B=2 ∆= 4+32 x=-2+-√36/2.1

c=-8 ∆=36 x=-2+-6/2

x1=-2+6/2 x1=4/2

x1=2

x2=-2-6/2 x2=-8/2

x2=-4

4)

a=1 ∆=b²-4a.c R)não existe raiz de

B=-5 ∆=25-64 número negativo.

c=8 ∆= -39

5)

a=2 ∆=b² -4.a.c x=-b + -√∆/2a

B=-8 ∆=64 -64 x=8+-√0/2.2

c=8 ∆=0 x=8/4 x=2

6)

a=1 ∆=b² - 4.a.c x=-b + - √∆/2a

B=-4 ∆=16+20 x=4+-√36/2.1

c=-5 ∆=36 x=4-+6/2

x1=4+6/2 x1=10/2

x1=5

x2=4-6/2 x2=-2/2

x2=-1

7)

a=-1 ∆=b² - 4.a.c x=-b + - √∆/2a

B=1 ∆=1+48 x=-1+-√49/2.1

c=12 ∆=49 x=-1+-7/2

x1=-1+7/2 x1=6/2=3

x2=-1-7/2

x2=-8/2 x2=-4

8)

a=-1 ∆=b² - 4.a.c x=-b + - √∆/2a

B=6 ∆=36-20 x=-6+-√16/2.(-1)

c=-5 ∆=16 x=-6+-4/-2

x1=-6+4/-2

x1=-2/-2 x1=-1

x2=-2-4/-2

x2=-6/-2 x=3

9)

a=6 ∆=b² - 4.a.c x=-b + - √∆/2a

B=1 ∆=1+24 x=-1+-√25/2a

c=-1 ∆=25 x=-1+-5/12

x1=-1+5/12 x1=4/12

x1=1/3

x2=-1-5/12 x2=-6/12

x2=-1/2

10)

a=3 ∆=b² - 4.a.c x=-b + - √∆/2a

B=-7 ∆=49-24 x=7-+√25/2.3

c=2 ∆=25 x=7+-5/6

x1=7+5/6 x1=12/6

x1=2

x2=7-5/6 x2=2/6

x2=1/3

11)

a=2 ∆=b² - 4.a.c x=-b + - √∆/2a

B=-7 ∆=49+120 x=7+-√169/2.2

c=-15 ∆=169 x=7+-13/4

x1=7+13/4 x1=20/4

x1=5

x2=7-13/4 x2=-6/4

x2=-3/2

12)

a=4 ∆=b² - 4.a.c x=-b + - √∆/2a

B=-12 ∆=144-144 x=12+-√0/2.4

c=9 ∆=0 x=12/8 x=3/2

13)

a=1 ∆=b² - 4.a.c x=-b + - √∆/2a

B=-1 ∆=1+48 x=1+-√49/2.1

c=-12 ∆=49 x=1+-7/2

x1=1+7/2 x1=8/2

x1=4

x2=1-7/2 x2=-6/2

x2=-3

14)

a=2 ∆=b² - 4.a.c x=-b + - √∆/2a

B=12 ∆=144-144 x=-12+-√0/2.2

c=18 ∆=0 x=-12/4 x=-3

15)

a=-4 ∆=b² - 4.a.c não possuí raiz

B=9 ∆=18+16 real

c=0 ∆=34

16)

a=25 ∆=b² - 4.a.c x=-b + - √∆/2a

B=-20 ∆=400-400 x=20+-√0/2.25

c=4 ∆=0 x=20/50 x=2/5

17)

a=-1 ∆=b² - 4.a.c não existe raiz de

B=2 ∆=4-60 número negativo.

c=-15 ∆=-56

18)

a=1 ∆=b² - 4.a.c não existe raiz de

B=3 ∆=6-8 número negativo.

c=2 ∆=-2

19)

a= 1 ∆=b² - 4.a.c não existe raiz de

B= 1 ∆=1-48 número negativo.

c=12 ∆=-47

20)

a=1 ∆=b2 - 4.a.c x=-b + - √∆/2a

B=-2 ∆=4-4 x=2+-√0/2.1

c=1 ∆=0 x=2/2 x=1

21)

a=1 ∆=b2 - 4.a.c x=-b + - √∆/2a

B=6 ∆=36-36 x=-6+-√0/2.1

c=9 ∆=0 x=-6/2 x=-3

Espero ter ajudado ;-)