Question

求适合2cos2x-1=0的x的集合

Answer 1

2cos2x-1=0

2cos2x=1

cos2x=1/2

2x=2kπ±π/3

所以 x=kπ±π/6,k∈Z

所以,所求集合为{x|x=kπ±π/6,k∈Z}