diff --git a/一些有趣的线代题目.md b/一些有趣的线代题目.md
index ed7526d..7127fe9 100644
--- a/一些有趣的线代题目.md
+++ b/一些有趣的线代题目.md
@@ -77,7 +77,7 @@ $$
 则 $P^{-1}ABP = P^{-1}BAP$
 
 $$
-\therefore P^{-1}APP^{-1}BP = P^{-1}BPP^{-1}APP
+\therefore P^{-1}APP^{-1}BP = P^{-1}BPP^{-1}AP
 $$
 
 设 $P^{-1}BP = \Lambda_2$