根号下x+根号下3-3x的值域
人气:418 ℃ 时间:2020-01-30 18:04:44
解答
易得:0≦x≦1
不妨令:x=sin²θ,θ∈[0,π/2]
则:3-3x=3(1-x)=3cos²θ
所以,y=sinθ+(√3)cosθ,θ∈[0,π/2]
由辅助角公式:y=2sin(θ+π/3),
θ∈[0,π/2]
则θ+π/3∈[π/3,5π/6]
则:sin(θ+π/3)∈[1/2,1]
所以,y∈[1,2]
即所求值域为[1,2]
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