f（x）=2sin（x/2+派/6）≤2
当x/2+π/6=2kπ+π/2,即x=4kπ+2π/3 ,f（x）=2sin（x/2+派/6）最大值为2,此时x的取值集合
{xlx=4kπ+2π/3 ,k∈Z}