Question

5) Resolva as equações do 2º grau.

a) x2 - 6x - 7 = 0 b) x2 - 2x -3 = 0 c) x2 - 7x - 8 = 0 d) x2 + 6x + 8 = 0 e) x2 + 10x + 25 = 0 f) x2 - 4x + 9 = 0​

Answer 1

Explicação passo-a-passo:

x² - 6x + 7 = 0

a= 1; b = -6; c = 7

D = -6² - 4 . 1 . 7

D = 36 - 28

D = 8

x' = -(-6) + V8

2 . 1

x' = 6 + V8

2

x" = -(-6) - V8

2 . 1

x" = 6 - V8

2

x² - 2x - 3 = 0

a= 1; b = -2; c = -3

D = -2² - 4 . 1 . (-3)

D = 4 + 12

D = 16

x' = -(-2) + 4

2 . 1

x' = 2 + 4

2

x' = 6

2

x' = 3

x" = -(-2) - 4

2 . 1

x" = 2 - 4

2

x'' = -2

2

x'' = -1

x² - 7x - 8 = 0

a= 1; b = -7; c = -8

D = -7² - 4 . 1 . (-8)

D = 49 + 32

D = 81

x' = -(-7) + 9

2 . 1

x' = 7 + 9

2

x' = 16

2

x' = 8

x" = -(-7) - 9

2 . 1

x" = 7 - 9

2

x'' = -2

2

x'' = -1

x² + 6x + 8 = 0

a= 1; b = 6; c = 8

D = 6² - 4 . 1 . 8

D = 36 - 32

D = 4

x' = -6 + 2

2 . 1

x' = -6 + 2

2

x' = -4

2

x' = -2

x" = -6 - 2

2 . 1

x" = -6 - 2

2

x'' = -8

2

x'' = -4

x² + 10x + 25 = 0

a= 1; b = 10; c = 25

D = 10² - 4 . 1 . 25

D = 100 - 100

D = 0

x' = -10 + 0

2 . 1

x' = -10 + 0

2

x' = -10

2

x' = -5

x" = -10 - 0

2 . 1

x" = -10 - 0

2

x'' = -10

2

x'' = -5

x² - 4x + 9 = 0

a= 1; b = -4; c = 9

D = -4² - 4 . 1 . 9

D = 16 - 36

D = -20