tanα=3^X ,tanβ=3^(-X),α-β=π/6,则X=_____.
1个回答

tanα=3^X

tanβ=3^(-X)

α-β=π/6

tan(α-β) = (tanα-tanβ)/(1+tanα tanβ) = tan(π/6)

{3^x-3^(-x)} / {1+ 3^x *3^(-x)} = √3/3

{3^x-3^(-x)} / {1+ 1} = √3/3

3^x-3^(-x) = 2√3/3

3^x-1/3^x = 2√3/3

(3^x)^2 - 1 = 2√3/3 *3^x

(3^x)^2 - 2√3/3 *3^x = 1

(3^x - √3/3 )^2 = 1+1/3 = 4/3

3^x - √3/3 = ± 2√3 /3

3^x = √3/3 ± 2√3 /3

3^x = - 2√3 /3(舍去)

3^x = √3

x=1/2