Tg(pi + x) = tgx
ctg(-x) = -ctg(x) = -1 / tgx
2tgx - 1 /tgx - 1 = 0
tgx не равен 0, поэтому домножим на него
2tg^2x - 1 - tgx = 0
t = tgx
2t^2 - t - 1 = 0
t = 1 t = -1/2
tgx = 1
x = pi/4 + pi * n, n ∈ Z
tgx = -1/2
x = arctg(-1/2) + pi * k, k ∈ Z
Ответ x = pi/4 + pi * n, n ∈ Z, x = arctg(-1/2) + pi * k, k ∈ Z