f(x)=4sinx[(√3/2)sinx+(1/2)cosx]-1
f(x)=2√3sin²x+2sinxcosx-1
f(x)=√3(1-cos2x)+sin2x-1
f(x)=2sin(2x-π/3)+(√3-1)
最小正周期是2π/2=π
当:x∈[-π/6,π/4]
则:2x-π/3∈[-2π/3,π/6]
sin(2x-π/3)∈[-1,1/2]
f(x)∈[√3-3,√3]
f(x)=4sinx[(√3/2)sinx+(1/2)cosx]-1
f(x)=2√3sin²x+2sinxcosx-1
f(x)=√3(1-cos2x)+sin2x-1
f(x)=2sin(2x-π/3)+(√3-1)
最小正周期是2π/2=π
当:x∈[-π/6,π/4]
则:2x-π/3∈[-2π/3,π/6]
sin(2x-π/3)∈[-1,1/2]
f(x)∈[√3-3,√3]