f(x^3)=lgx(x>0)求f(x)

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f(x^3)=lgx(x>0)求f(x)

f(x^3)=lgx(x>0)求f(x)
f(x^3)=lgx(x>0)求f(x)

f(x^3)=lgx(x>0)求f(x)
f(x^3) = lg x
let y =x^3
f(y) = lg y^(1/3) = (1/3)lgy
ie
f(x) = (1/3) lgx

f(x)=lg(x^(1/3))
f(x)=(1/3)lgx

f(x^3)=lgx(x>0)求f(x)
利用变量的等效变换,令t=x³,则x=t^(1/3) (x>0,t>0)
f(x^3)=f(t)
=lgx(x>0)
=lg(t^(1/3))
=1/3lgt
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