Question

quero resolver essa equação x2+2x-8=0

Answer 1

Δ  = 4 + 32
Δ = 36

x = -2 +-√36/2
x = -2 +-6/2

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

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

Answer 2

x² + 2x - 8 = 0

a = 1; b = 2; c = -8

x = [- b ± √(b² - 4ac)] / 2a
x = [- 2 ± √(2² - 4 · 1 · [-8])] / 2 · 1
x = [- 2 ± √(4 + 32)] / 2
x = [- 2 ± √36] / 2
x = [- 2 ± 6] / 2
x' = [- 2 + 6] / 2 = 4 / 2 = 2
x'' = [- 2 - 6] / 2 = -8 / 2 = -4

S = {-4, 2}

Espero ter ajudado. Valeu!