## Calculus: Early Transcendentals (2nd Edition)

$\ln$ |x| +C
Derivative of $\ln$ |x| is $\frac{1}{x}$. So, the antiderivatives of $\frac{1}{x}$, i.e., $\int \frac{1}{x}dx= \ln |x| +C$ where C is arbitrary constant.