Several of the solutions to the problems have a great deal more detail than will be expected of the students in the course. It is imporatnt to make sure that the idea that you use to solve a problem is explained. Calculations that are left out should also be justified. If you remember a theorem or an exercise you have done then you can apply it (with the assertion of where the fact comes from). If the result is “bogus” however you will almost certainly suffer the consequences.