$ \huge \ha{ \int x^n \d{x} &= \frac{x^{n+1}}{n + 1} + C \color{gray} \iff\color{white} \ne 1 \\ \int x^{-1}\d{x} &= \ln \left| {x} \right| + C } $ Logical reverse of the [[Derivative Power Rule|Derivative Power Rule]].