5.5 The Substitution Rule/67

$\int _{e}^{e^{4}}{\frac {dx}{x{\sqrt {lnx}}}}$ = $\int _{1}^{4}{\frac {1}{u}}du$ = Failed to parse (unknown function "\u"): {\displaystyle \int_{1}^{4}\u^\frac{-1}{2}du}