Question

Equação de segundo grau completa

a= x² - 81 = 0

b= x² + 2x = 0

c= x² - 3x - 28 = 0

d= x² - 2x = 2x - 4

????​

Answer 1

Resposta:

a) x^2 - 81 = 0

x^2 = 81

x = √81

x = 9

b) x^2 + 2x = 0

∆ = 2^2 - 4 × 1 × 0

∆ = 4

x = -2 +-√4 / 2 × 1

x' = -2 + 2 / 2 = 0

x" = -2 - 2 / 2 = -2

c) x^2 - 3x - 28 = 0

∆ = 9 + 112 = 121

x' = +3 + 11 / 2 = 7

x" = +3 - 11 / 2 = -4

d) x^2 - 2x = 2x - 4

∆ = 16

x' = 0 + 4 / 2 = 2

x" = 0 - 4 / 2 = -2

OBS:

∆ = b^2 - 4 × a × c

x = -b + ou - √∆ / 2 × a