diff --git a/src/4_vector_spaces_QM.md b/src/4_vector_spaces_QM.md
index e55660eb7f01626da2e5cec0c7cab41546dec684..b28f1b70a7a3be711c8df311c80659080726ff99 100644
--- a/src/4_vector_spaces_QM.md
+++ b/src/4_vector_spaces_QM.md
@@ -243,7 +243,7 @@ $$
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 Let $a=6+5i$ and answer the following questions:
 
-*(a)*. Calculate $a|A\rangle$, $a |B\rangle$, and $a( |A\rangle+|B\rangle)$. Show that $a(|A\rangle+|B\rangle)=a|A\rangle+|B\rangle)$.
+*(a)*. Calculate $a|A\rangle$, $a |B\rangle$, and $a( |A\rangle+|B\rangle)$. Show that $a(|A\rangle+|B\rangle)=a|A\rangle+a|B\rangle$.
 
 *(b)*. Find the inner products $\langle A | B\rangle$ and $\langle B | A\rangle $. What is the relationship between them?