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问题: 取值范围

若sinx=(1-m)/(2m+3)且x∈[-π/6,π/6]则m的取值范围

解答:

sinx = (1-m)/(2m+3)
--->2sinx = [5-(2m+3)]/(2m+3) = 5/(2m+3)-1
--->2m+3 = 5/(1+2sinx)
--->m = 5/(1+2sinx)-3

x∈[-π/6,π/6]--->sinx∈[-1/2,1/2]--->1+2sinx∈[0,2]
--->5/(1+2sinx)∈[5/2,+∞)
--->m = 5/(1+2sinx)-3 ∈[-1/2,+∞)