Question

Resolva na variavel x, a equaçao: x2 - 4x + 4cos2 a=0

Answer 1

(x-2)² - (x-1)² = 10 - x²
x² - 4x + 4 - x² + 2x - 1 = 10 - x²
x² - 2x - 7 = 0

Δ = b² - 4ac
Δ = (-2)² - 4(1)(-7)
Δ = 4 + 28
Δ = 32

x = (-b +- √Δ)/2a
x = (2 +- √32)/2
x = (2 +- √16*2)/2
x = (2 +- 4√2)/2
x = (1 +- 2√2)

x1 = 1 + 2√2
x2 = 1 - 2√2