diff --git a/source/02-FN/03.ptx b/source/02-FN/03.ptx
index 8f585587..42ccff57 100644
--- a/source/02-FN/03.ptx
+++ b/source/02-FN/03.ptx
@@ -803,7 +803,7 @@
         </statement>
         <answer>
           <p>
-            <m>(-2,-0.5)U(2.25,\infty)</m>
+            <m>(-2,-0.5)\cup(2.25,\infty)</m>
           </p>
         </answer>
       </task>
@@ -879,4 +879,4 @@
         <title>Videos</title>
         <p>It would be great to include videos down here, like in the Calculus book!</p>
     </subsection> -->
-</section>
\ No newline at end of file
+</section>