Question

3. Resolva as equações de 2º grau:
b) 3x² - 2x - 1 = 0
c) X² +8x + 16 = 0
d) 5x²+4x-1=0
e) 2x² +5x-3=0
f) x² – 3x - 4 = 0
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Answer 1

Resposta:

b) ∆ = b² – 4ac

∆ = 4 + 12

∆ = 16

x = –b ± √∆ / 2a

x = 2 ± √16 /6

x = 2 ± 4 / 6

x' = 6/ 6

x' = 1

x" = –2/6

x" = –2/6x" = –1/3

c) ∆ = 64 – 52

∆ = 12

x = –8 ± 2√3/2

x' = – 8√3

x" = 8√3

d) ∆ = 16 + 30

∆= 36

x = –4 ± 6 / 10

x' = – 2/10 ou – 1/5

x" = –10/10

x" = – 1

e)∆ = 25 + 24

∆= 48

x = –5 ± 7/ 4

x' = 2/4 ou 1/4

x" = –12/4

x" = –3

f) ∆= 9 + 16

∆= 25

x = 3 ± 5/ 2

x' = 8/2

x' = 4

x" = –2/2

x" = –1