You are right, the Socratic app does use machine learning to give instant solutions, but that does not apply to the math solver, it only applies to how the app finds content related to the question.
As you know, the app works by allowing students to take photos of their questions. When you take a photo of your question, the app shows you content that you can use to answer the question--explainers, Q&A, videos, and definitions
That is where machine learning comes into play. The team used millions of questions to train the AI to recognize the content needed to help the student answer the question and do so as fast and as accurate as possible.
The algorithm that the math solver uses, which the team designed from scratch, is not based on using answers to train the AI
So, to answer your question, your answers will not be used to train the AI that makes the math solver work.