Solve the equation sec^2 x+ 2tan x = 0, 0 ≤ x ≤ 2π. IB May 2017 Exam

sec^2 x+ 2tan x = 0
use the fact that sec^2 x= tan^2 x +1
tan^2 x + 2tan x + 1 =0
(tan x +1)^2 = 0 tan x = - 1
x=3π/4, x= 7π/4