Apply suggestion 'an' -> 'a'

Co-authored-by: Elena Shmoylova <eshmoylova@users.noreply.github.com>

chapters/functions.tex

@@ -1679,7 +1679,7 @@ \section{Declaring Inverses of Functions}\label{declaring-inverses-of-functions}
 end NotSurjective;
 \end{lstlisting}
 As the value of \lstinline!x! varies over the interval $[-1,\, 1]$, but the range of \lstinline!cbrtPos! is only $(0, \infty)$, the informal codomain of \lstinline!cbrtPos! cannot be restricted such that the surjectiveness is fulfilled.
-A valid solution to the equation in \lstinline!x! and \lstinline!y! must satisfy $\text{\lstinline!y!} > 0$, and when no \lstinline!inverse! annotation is given, an violation will be detected by a nonlinear solver applied directly to the equation.
+A valid solution to the equation in \lstinline!x! and \lstinline!y! must satisfy $\text{\lstinline!y!} > 0$, and when no \lstinline!inverse! annotation is given, a violation will be detected by a nonlinear solver applied directly to the equation.
 When the (invalid) inverse provided by the \lstinline!inverse! annotation is used, however, the equation gets transformed into
 \begin{lstlisting}[language=modelica]
   y = cube(x);