Merge pull request #83 from clark-archer/section-12.2-typos

Fix some typos in section 12.2.

public/textbook/integrals.tex

@@ -511,9 +511,9 @@ \section{Riemann Sums}
 \end{tikzpicture}
 \caption{A plot of $f(x)$ along with the partition 
 \[
-[x_0,x_1]\cup [x_1, x_2]\cup [x_2,x_3]\cup [x_3,x_4]\cup[x_4,x_5] = [a,b]
+[x_0,x_1]\cup [x_1, x_2]\cup [x_2,x_3]\cup [x_3,x_4] = [a,b]
 \]
-and the $y$-values $f(x_0^*)$, $f(x_1^*)$, $f(x_2^*)$, $f(x_3^*)$, $f(x_4^*)$.}
+and the $y$-values $f(x_0^*)$, $f(x_1^*)$, $f(x_2^*)$, $f(x_3^*)$.}
 \label{figure:areacompute2}
 \end{marginfigure}
 For each subinterval pick a point $x_i^*\in [x_i,x_{i+1}]$ and
@@ -626,7 +626,7 @@ \section{Riemann Sums}
 where $x_i^*\in [x_i,x_{i+1}]$.
 \end{definition}
 
-There are actually at least five special Riemann sums, \textit{left},
+There are actually at least five special Riemann sums: \textit{left},
 \textit{right}, \textit{midpoint}, \textit{upper}, and \textit{lower}.
 
 \begin{definition}