Ответы и объяснения

2014-02-18T11:08:55+00:00
Cos(2x) - 4√2cos(x) + 4 = 0
=> (2cos^2(x) - 1) - 4√2cos(x) + 4 = 0
=> 2cos^2(x) - 4√2cos(x) + 3 = 0
=> cos(x) = (4√2 +- √8) / 4
=> cos(x) = √2 +- (√2)/2, -1 <= cos(x) <= 1
=> cos(x) = √2 - (√2)/2 = (√2)/2
=> x = +-pi/4 + 2pi*k, k ∈ Z