The domain of f(x)=1|cosx|+cosx is
[−2nπ,2nπ],n∈Z
(2nπ,2n+1¯π),n∈Z
(4n+1)π2,(4n+3)π2,n∈Z
(4n−1)π2,(4n+1)π2,n∈Z
cosx +cosx = 0 if cosx ≤0
= 2 cosx, if cosx >0
for fx to be defined , cos x >0 ⇒ x∈ 4n-1π2,4n+1π2 , n∈Z i.e 1st and 4th quadrants