## Thomas' Calculus 13th Edition

$f(x)$ does not need to be defined at $x=1$
The existence and non-existence of the $\lim\limits_{x \to c}f(x)=l$ does not depend on whether the function is defined or not defined at x=c. Thus, the function $f(x)$ cannot be defined at $x=1$so, the limit of the function cannot be determined.