Update app.py

app.py

@@ -293,7 +293,8 @@ NOTE: For eigenvalue problems, use 'lam = Symbol('lam')' instead of importing fr
    print("Indefinite integral:")
    print(indefinite_integral)
    ```
-
+   NOTE: If there was an indefinite integral before you manipulated the expression, always try the above approach before proceeding. 
+   
    For numerical verification, always use definite integrals:
    ```python
    # Use specific bounds and verify numerically