[likelihood] fixed exercises

likelihood/exercises/exercises01.tex

@@ -130,8 +130,8 @@ standard deviation $\sigma_i$:
   \part \label{mleslopefunc} Write a function that takes two vectors
   $x$ and $y$ containing the data pairs and returns the slope,
   computed according to this equation. For simplicity we assume
-  $\sigma_i=\sigma_j=\sigma$ for all $1 \le i \le n$ and $1 \le j \le
-  n$. How does this simplify the equation for the slope?
+  $\sigma_i=\sigma$ for all $1 \le i \le n$. How does this simplify
+  the equation for the slope?
   \begin{solution}
     \lstinputlisting{mleslope.m}
   \end{solution}