求此函数取得最大最小值的自变量x的集合.
3个回答

当cos(1/2x-π/6) = -1时,函数Y=-3/2cos(1/2x-π/6) 有最大值3/2,

故有:1/2x-π/6 = ±π

由1/2x-π/6 = π 得x=7π/3,

由1/2x-π/6 = -π 得x= -5π/3.

所以函数Y=-3/2cos(1/2x-π/6) x属于[-2π,2π] 取最大值时x∈{7π/3,-5π/3}

当cos(1/2x-π/6) = 1时,函数Y=-3/2cos(1/2x-π/6) 有最小值-3/2,

故有:1/2x-π/6 = -2π、0、2 ,

由1/2x-π/6 = -2π得x= -11π/3,

由1/2x-π/6 = 0得x= π/3,

由1/2x-π/6 = 2π得x= 13π/3.

所以函数Y=-3/2cos(1/2x-π/6) x属于[-2π,2π] 取最小值时x∈{-11π/3,π/3,13π/3}