Correct dot product example calculation result (#421)

public/content/lessons/2016/dot-products/index.mdx

@@ -32,7 +32,7 @@ Numerically, if you have two vectors of the same dimension, two lists of numbers
 For instance, two vectors of length two dotted together looks like:
 
 $$
-\left[\begin{array}{l}1 \\ 2\end{array}\right] \cdot \left[\begin{array}{l}3 \\ 4\end{array}\right] = 1 \cdot 3+2 \cdot 4 = 9
+\left[\begin{array}{l}1 \\ 2\end{array}\right] \cdot \left[\begin{array}{l}3 \\ 4\end{array}\right] = 1 \cdot 3+2 \cdot 4 = 11
 $$
 
 And two vectors of length four dotted together looks like: