## Precalculus (6th Edition) Blitzer

The correct fill for the blank provided in the statement is $a$.
In case of limits involving an identity function, for any value of $a$, as $x$ gets closer to $a$, the corresponding value of $f\left( x \right)$ is just as close to $a$. That is: For the identity function $f\left( x \right)=x$, $\underset{x\to a}{\mathop{\lim }}\,f\left( x \right)=\underset{x\to a}{\mathop{\lim }}\,\text{ }x=a$. Where $a$ is any number.