Question

若函数f(x)=2sin（kx/π+π/4）的周期在（2/3,3/4）内,则k的一切可取的正整数值是?

Answer 1

T=2π/ω

=2π/(k/π)

=2*π^2*k

由题T∈(2/3,3/4)

解得k∈(8/3π^2,3π^2)

8/3*3.14^2=26.29

3*3.14^2=29.58

∴k∈{27,28,29}