The end-of-chapter exercises provide you an opportunity to practice the concepts covered up to that point in the book. Since the chapters build upon previous onces, it is recommended that you work through the exercises before moving on to solidify the concepts.
Note: The solutions provided here are crafted to only use knowledge gained up to and through the chapter in question, so an exercise in chapter 3 has a solution that only uses content from chapters 1-3. For some exercises, there are also multiple ways of arriving at the solution.