Question

Resolva as equações abaixo:
x² – 9 = 0
x² + 8x = 0
x² + 5x + 4 = 0​

Answer 1

a) x² - 9 = 0

x² = 9

x = ±3

x' = -3

x" = 3

b) x² + 8x = 0

x × (x + 8) = 0

x = 0

x + 8 = 0

x' = 0

x" = -8

c) x² + 5x + 4 = 0

Δ = 5² - 4×1×4

Δ = 25 - 16

Δ = 9

$x= \frac{-5+-\sqrt{9} }{2.1}$

$x= \frac{-5+-3}{2}$

$x'=\frac{-5-3}{2}$

$x"=\frac{-5+3}{2}$

$x' = -4\\x" = -1$