diff --git a/study/kernel/01-process/05-schedule/04-cfs/02-vruntime/README.md b/study/kernel/01-process/05-schedule/04-cfs/02-vruntime/README.md
index 3b8fd1c..16033c9 100644
--- a/study/kernel/01-process/05-schedule/04-cfs/02-vruntime/README.md
+++ b/study/kernel/01-process/05-schedule/04-cfs/02-vruntime/README.md
@@ -130,7 +130,9 @@ $$	delta =delta \times \dfrac{NICE\_0\_LOAD}{curr->se->load.weight}   ;(if curr.
 那么`curr->vruntime += calc_delta_fair(delta_exec, curr);` 即相当于如下操作
 
 
-$\dfrac{a}{b}$
+$\frac{a}{b}$
+
+
 | 条件 | 公式 |
 |:-------:|:-------:|
 | curr.nice != NICE_0_LOAD | $curr->vruntime += delta\_exec \times \dfrac{NICE\_0\_LOAD}{curr->se->load.weight}    (if )$ |