diff --git a/doc/pub/week39/html/week39-reveal.html b/doc/pub/week39/html/week39-reveal.html
index 5a7bd4d43..9c2d33cc5 100644
--- a/doc/pub/week39/html/week39-reveal.html
+++ b/doc/pub/week39/html/week39-reveal.html
@@ -807,7 +807,7 @@ $$
 <p>&nbsp;<br>
 $$
 \begin{equation*}
-\boldsymbol{x}_{k+1}=\boldsymbol{x}_k-\alpha_k\boldsymbol{r}_{k},
+\boldsymbol{x}_{k+1}=\boldsymbol{x}_k+\alpha_k\boldsymbol{r}_{k},
  \end{equation*}
 $$
 <p>&nbsp;<br>
diff --git a/doc/pub/week39/html/week39-solarized.html b/doc/pub/week39/html/week39-solarized.html
index 02f730271..519b915b5 100644
--- a/doc/pub/week39/html/week39-solarized.html
+++ b/doc/pub/week39/html/week39-solarized.html
@@ -841,7 +841,7 @@ $$
 <p>leading to the iterative scheme</p>
 $$
 \begin{equation*}
-\boldsymbol{x}_{k+1}=\boldsymbol{x}_k-\alpha_k\boldsymbol{r}_{k},
+\boldsymbol{x}_{k+1}=\boldsymbol{x}_k+\alpha_k\boldsymbol{r}_{k},
  \end{equation*}
 $$
 </div>
diff --git a/doc/pub/week39/html/week39.html b/doc/pub/week39/html/week39.html
index 48dfcbf03..2240c704a 100644
--- a/doc/pub/week39/html/week39.html
+++ b/doc/pub/week39/html/week39.html
@@ -918,7 +918,7 @@ $$
 <p>leading to the iterative scheme</p>
 $$
 \begin{equation*}
-\boldsymbol{x}_{k+1}=\boldsymbol{x}_k-\alpha_k\boldsymbol{r}_{k},
+\boldsymbol{x}_{k+1}=\boldsymbol{x}_k+\alpha_k\boldsymbol{r}_{k},
  \end{equation*}
 $$
 </div>
diff --git a/doc/pub/week39/ipynb/ipynb-week39-src.tar.gz b/doc/pub/week39/ipynb/ipynb-week39-src.tar.gz
index 6482edc57..da718dc89 100644
Binary files a/doc/pub/week39/ipynb/ipynb-week39-src.tar.gz and b/doc/pub/week39/ipynb/ipynb-week39-src.tar.gz differ
diff --git a/doc/src/week39/week39.do.txt b/doc/src/week39/week39.do.txt
index 48d1a7a5b..c703f04bd 100644
--- a/doc/src/week39/week39.do.txt
+++ b/doc/src/week39/week39.do.txt
@@ -515,7 +515,7 @@ which gives
 leading to the iterative scheme
 !bt
 \begin{equation*}
-\bm{x}_{k+1}=\bm{x}_k-\alpha_k\bm{r}_{k},
+\bm{x}_{k+1}=\bm{x}_k+\alpha_k\bm{r}_{k},
  \end{equation*}
 !et
 !eblock