∫1xlnx dx=\displaystyle\int \dfrac{1}{x \ln x}\,dx =∫xlnx1dx=A1(lnx)2+C\dfrac{1}{(\ln x)^2} + C(lnx)21+CBln(ln∣x∣)+C\ln(\ln|x|) + Cln(ln∣x∣)+CCln(lnx)+C\ln(\ln x) + Cln(lnx)+Ccheck_circleDlnx⋅x+C\ln x \cdot x + Clnx⋅x+CExplanationu=lnxu = \ln xu=lnx, du=dx/xdu = dx/xdu=dx/x. ∫du/u=ln∣u∣=ln(lnx)\int du/u = \ln|u| = \ln(\ln x)∫du/u=ln∣u∣=ln(lnx) (assuming lnx>0\ln x > 0lnx>0).