\int_{e}^{e^4}\frac{dx}{x\ln x}
for the above question you could easily use the substitution x=lnx but if we were to use parts, we get:
2\int_{e}^{e^4}\frac{dx}{x\ln x}=[\frac{\ln x}{\ln x}]^{e^4}_{e}
by letting u=\frac{1}{\ln x} and v=\ln xdx
Whats with that? How can you have 1...