Discontinuities are a little more challenging to identify when working with formulas than when working with graphs. One reason for the added difficulty is that when working with a function formula you have to dig into your memory bank and retrieve fundamental properties about certain types of functions.
If \(y\) is a function of \(u\text{,}\) defined by \(y = \fe{\ln}{u}\text{,}\) what is always true about the argument of the function, \(u\text{,}\) over intervals where the function is continuous?