f(x)=3sin(2x-π/3)+2
f(x)的最大值=3+2=5
2x-π/3=2kπ+π/2
x=kπ+π/3
2)2x-π/3在[2kπ-π/2,2kπ+π/2]单调递增
x在[kπ-π/12,kπ+5π/12]单调递增