Answer:
x=0 or x=pi / x=πn
Explanation:
cos2x + 3 = 4
subtract 3 from both sides
cos2x = 1
take the inverse cos/arccos of both sides
arccos(cos2x) = arccos(1)
2x=0 or 2x=2pi
divide both sides by 2
x=0 or x=pi
beyond (0,2pi) for every possible answer you should do x=(pi)n since any multiple of pi gives you the same answer