diff --git a/docs/10.md b/docs/10.md
index 3c652326da8b07bf51348f12e97938bb822fea6a..5de880c137f048b56bb968031d0bdae18e58be4d 100644
--- a/docs/10.md
+++ b/docs/10.md
@@ -36,5 +36,5 @@ $$
 
 在无穷时间步的情况下，我们有：
 $$
-\theta^{*} = \mathop{\arg\max}_{\theta}\sum _{t=1}^{\infty} \mathbb{E} _{(s,a) \sim P _{\theta}(s,a)[\gamma^t r(s,a)]}
+\theta^{*} = \mathop{\arg\max}_{\theta}\sum _{t=1}^{\infty} \mathbb{E} _{(s,a) \sim P _{\theta}(s,a)}[\gamma^t r(s,a)]
 $$
\ No newline at end of file