Fix matrix example

chapter24.tex

@@ -590,33 +590,33 @@ makes a mistake when it reports that $AB=C$.
 For example, 
 \[
  \begin{bmatrix}
-  2 & 4 \\
-  1 & 6 \\
+  6 & 8 \\
+  1 & 3 \\
  \end{bmatrix}
 \neq
  \begin{bmatrix}
-  0 & 5 \\
-  7 & 4 \\
+  8 & 7 \\
+  3 & 2 \\
  \end{bmatrix},
 \]
 but
 \[
  \begin{bmatrix}
-  2 & 4 \\
-  1 & 6 \\
+  6 & 8 \\
+  1 & 3 \\
  \end{bmatrix}
  \begin{bmatrix}
-  1 \\
   3 \\
+  6 \\
  \end{bmatrix}
 =
  \begin{bmatrix}
-  0 & 5 \\
-  7 & 4 \\
+  8 & 7 \\
+  3 & 2 \\
  \end{bmatrix}
  \begin{bmatrix}
-  1 \\
   3 \\
+  6 \\
  \end{bmatrix}.
 \]
 However, in practice, the probability that the