Question

considerando que x e R, resolva as equações

A)(x-4)^2 = 81
B)(x+1)^2=100
C)(4x+2)^2=36
D)(3x-9)^2=36
E)(x+5)^2=1
F)(x+5)^2=-1

Answer 1

Resposta:

a)

x² - 8x + 16 = 81

x² - 8x + 16 - 81 = 0

x² - 8x - 65 = 0

Δ = (-8)² - 4.1.(-65)

Δ = 64 + 260

Δ = 324

x = $\frac{-(-8)\sqrt{324} }{2.1}$

x = $\frac{8+-18}{2}$

x' = $\frac{8+18}{2}$

x' = $\frac{26}{2}$

x' = 13

x'' = $\frac{8-18}{2}$

x'' = $\frac{-10}{2}$

x'' = -5