Respostas

2014-07-20T14:27:17-03:00
A) 

(2a + 3b)² = 0
2a² + 2.2a.3b + 3b² = 0
4a + 12ab + 9b = 0
Δ = 12² - 4.4.9
Δ = 144 - 144
Δ = 0

x = - 12 + - √ 0 / 8
x = - 12 + - 0 / 8

x ' e x '' = - 12 + - 0 / 8 = - 12 / 8 = - 3 / 2


b)

(a + 5b)² = 0
a² + 2.a.5b + 5b² = 0
a² + 10ab + 25b = 0
Δ = 10² - 4.1.25
Δ = 100 - 100
Δ = 0

x = - 10 + - √ 0 / 2
x = - 10 + - 0 / 2 

x ' e x '' = - 10 + - 0 / 2 = - 10 / 2 = - 5