fix rendering

Author: yzh119

_posts/2025-03-10-sampling.md

@@ -251,7 +251,9 @@ The sum of the coefficient $\sum_{\substack{r \notin T \\ p_r > \tau}} \frac{p_r
 
 $$0 \leq \frac{W(\tau)}{S(\tau)} < 1$$
 
-Suppose $\tau^*$ is the pivot where $\left|\Delta_j(\tau)\right|$ reach its maximum, if it's positive, we have:
+Suppose $\tau^*$ is the pivot where 
+$$|\Delta_j(\tau)|$$
+reach its maximum, if it's positive, we have:
 
 $$
 |\Delta_j(\tau^*)| \leq \sum_{\substack{r \notin T \\ p_r > \tau^*}}