Question: Create a professional educational mathematics video explaining the question and solution above.
1. The user requests a professional educational mathematics video explaining a question and its solution.
2. The video should use a clear, natural AI-generated voice without showing a human face or real person's voice.
3. All mathematical equations must be displayed clearly on screen.
4. The solution should be revealed step-by-step, mimicking a teacher writing on a digital blackboard.
5. The video must explain the uniqueness of prime factorisation in part (a).
6. It must explain why finding two distinct inputs with the same output proves a function is not injective in parts (b) and (c).
7. Calculations and correct mathematical reasoning must not be skipped or altered.
8. The final conclusion should be highlighted.
9. The style should be a clean whiteboard with readable mathematical notation.
10. Captions should be added and the video should be downloadable.
Note: For video creation, please visit the video page.