求下列函数的值域 (1)y=3sin(2x+π/2)-1 (x∈[-π/4,π/3]) (2)y=(cosx)^2-3cosx+1 (3)y=(cosx)^2-2cosx+1
求下列函数的值域 (1)y=3sin(2x+π/2)-1 (x∈[-π/4,π/3])
(2)y=(cosx)^2-3cosx+1 (3)y=(cosx)^2-2cosx+1 （x∈[-π/4,π/3])