diff --git a/meanValueTheorem/exercises/maxMinFirstDerivativeTest4.tex b/meanValueTheorem/exercises/maxMinFirstDerivativeTest4.tex
index 4d88924c1..4407352dd 100644
--- a/meanValueTheorem/exercises/maxMinFirstDerivativeTest4.tex
+++ b/meanValueTheorem/exercises/maxMinFirstDerivativeTest4.tex
@@ -23,7 +23,7 @@
 $$
 f'(x) = \frac{\answer{x^2-2x-8}}{(x-1)^2}
 $$
-The function $f$ has two critical points in the set $(-\infty,1)\cup (1,\infty)$. 
+The function $f$ has two critical points in the set $(-\infty,1)\cup (1,\infty)$ (note that we have to exclude 1 since it is not in the domain so $f$ is not defined there). 
  If we call these points $a$ and $b$ and order them such
 that $a < b $, then
 $$