Question

Resolva
a) x²- 4x - 5=0
b) x² + x +3= 0
C) 3x² +x -4=0

Answer 1

Explicação passo-a-passo:

a) x² - 4x - 5 = 0

a= 1; b = -4; c = -5

Δ = (-4)² - 4 . 1 . (-5)

Δ = 16 + 20

Δ = 36

x = (-b ± √Δ)/2a

x = ( - (-4) ± √36)/2 . 1

x = (4 ± 6)/2

x' = (4 + 6)/2

x' = (10)/2

x' = 5

x'' = (4 - 6)/ 2

x = -2/ 2

x'' = -1

S = {(-1, 5)}

b) x² + x + 3 = 0

a= 1; b = 1; c = 3

Δ = 1² - 4 . 1 . 3

Δ = 1 - 12

Δ = -11

c) 3x² + x - 4 = 0

a= 3; b = 1; c = -4

Δ = 1² - 4 . 3 . (-4)

Δ = 1 + 48

Δ = 49

x = (-b ± √Δ)/2a

x = ( - 1 ± √49)/2 . 3

x = (-1 ± 7)/6

x' = (-1 + 7)/6

x' = (6)/6

x' = 1

x'' = (-1 - 7)/ 6

x = -8/ 6

x'' = -4/3

S = {(-4/3, 1)}