Question

C) x²+2x-8=0
D) x²-5x+8=0
E)2x²-8x+8=0
F)x²-4x-5=0

Answer 1

C) x² + 2x - 8 = 0
a = 1, b = 2, c = -8

Δ = b² - 4 . a . c

Δ = 2² - 4 . 1 . (-8)
Δ = 4 + 32
Δ = 36

x = – b ± √Δ / 2.a

x = - 2 ± √36 / 2.1
x = - 2 ± 6 / 2

x' = - 2 + 6 / 2
x' = 4 / 2
x' = 2

x'' = - 2 - 6 / 2
x'' = - 8 / 2
x'' = - 4



D) x²- 5x + 8 = 0
a = 1, b = - 5, c = 8

Δ = b² - 4 . a . c

Δ = - 5² - 4 . 1 . 8
Δ = 25 - 32
Δ = - 7
Delta não tem raiz real



E) 2x² - 8x + 8 = 0
a = 2, b = - 8, c = 8

Δ = b² - 4 . a . c

Δ = - 8² - 4 . 2 . 8
Δ = 64 - 64
Δ = 0

x = – b ± √Δ / 2.a

x = 8 ± √0 / 2.2
x = 8 ± 0 / 4

x' = 8 + 0 / 4
x' = 8 / 4
x' = 2

x'' = 8 - 0 / 4
x'' = 8 / 4
x'' = 2



F) x² - 4x - 5 = 0
a = 1, b = - 4, c = - 5

Δ = b² - 4 . a . c

Δ = - 4² - 4 . 1 . - 5
Δ = 16 + 20
Δ = 36

x = – b ± √Δ / 2.a

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