解:令 t =ln x,
则 x =e^t,
所以 ∫ ln (ln x) dx = ∫ (e^t) (ln t) dt
= ∫ (ln t) d(e^t)
= (e^t) (ln t) -∫ [ (e^t)/t ] dt
= (e^t) (ln t) -∫ d(e^t) /t
= (e^t) (ln t) -∫ dx /(ln x).
lnlnx的原函数是什么希望能解答下
解:令 t =ln x,
则 x =e^t,
所以 ∫ ln (ln x) dx = ∫ (e^t) (ln t) dt
= ∫ (ln t) d(e^t)
= (e^t) (ln t) -∫ [ (e^t)/t ] dt
= (e^t) (ln t) -∫ d(e^t) /t
= (e^t) (ln t) -∫ dx /(ln x).