Section 11.1 Limits
We can use the
limit() command to evaluate the limit of a function as \(x\) approaches \(a\text{.}\) The limit() command needs two parameters. The first parameter is the expression and the second parameter gives the value for a variable to approach.
Aside
The order of the parameters in the
limit() command is important. An error message will be displayed if you switch the order of the parameters in the command and then try to execute it.
> f(x) := x^2 + 2*x -4;
\begin{equation*}
\displaystyle f\, := \,x\mapsto {x}^{2}+2\,x-4
\end{equation*}
> limit(f(x), x=3);
\begin{equation*}
\displaystyle 11
\end{equation*}
In this next example, it is important to note that \(h=0\) here means that \(h\) approaches \(0\text{,}\) but we are not simply substituting \(h=0\) into the expression. In fact, this expression is undefined at \(h=0\text{.}\)
> limit((f(x+h) - f(x))/h, h=0);
\begin{equation*}
\displaystyle 2x+2
\end{equation*}
