Answer:
Step-by-step explanatio(cosx+1)(2cos^2x-3cosx-2)=0
set each factor equal to 0
cosx+1=0
cosx=-1
cos is -1 at x=∏=180º
2cos^2x-3cosx-2=0
factor
(2cosx+1)(cosx-2)=0
set each factor equal to 0
2cosx+1=0
2cosx=-1
cosx=-1/2
cos is -1/2 at x=2∏/3=120º and at x=4∏/3=240º
cosx-2=0
cosx=2
the range of cos is [-1,1] which doesn't include 2n:
