Question

A) x² = 64
B) 9x² - 9 = 0
C) 12x² = 48
D) x² = 5
E) x² + 81 = 0

Answer 1

x² - 81 = 0

x² = + 81

x = ± √81

x =± 9

S{- 9 ; + 9}

Ou pela fórmula de Bhaskara:

x² - 81 = 0

a = 1 b = 0 c = - 81

Δ = b² - 4.a.c

Δ = (0)² - 4.(1).(- 81)

Δ = 0 + 324

Δ = 324

x = - b ± √Δ

2.a

x = - (0) ± √324

2.1

x = 0 ± 18

2

x'= 0 + 18 = 18 = 9

2 2

x"= 0 - 18 = - 18 = - 9

2 2

S{- 9 ; 9}

DR.ADRIANO