I will analyze the image you provided to extract the mathematical content and then proceed to help you with your request.The image contains exercises from a textbook or worksheet, with one of the problems involving $P_{n+1}$. However, to assist you effectively, I need to know which specific problem you are focusing on.

If you are looking for a solution related to a particular problem or concept in the image, please clarify. For example, is the question asking about recurrence relations, sequences, or something specific about $P_{n+1}$?

Let me know how you'd like to proceed!