diff --git a/advanced-math/exercise/3-derivative-and-differentiate/derivative-and-differentiate.tex b/advanced-math/exercise/3-derivative-and-differentiate/derivative-and-differentiate.tex
index ac3dd62..053599b 100644
--- a/advanced-math/exercise/3-derivative-and-differentiate/derivative-and-differentiate.tex
+++ b/advanced-math/exercise/3-derivative-and-differentiate/derivative-and-differentiate.tex
@@ -285,6 +285,7 @@ $\dfrac{\rm{d}^2y}{\rm{d}\textit{x}^2}=\dfrac{\rm{d}\left(\dfrac{\rm{d}\textit{y
 
 \subsection{单调性与凹凸性}
 
+
 \subsection{极值与最值}
 
 \subsection{函数图像}