QCM on quadratic forms, equations and inequalities

To each question, there is one, and only one correct answer. Each correct answer has 2 points, while a wrong answer takes 0.5. The lack of response does not report or render any point.
Note: Even if questions are presented as a QCM where only a single "click" is required to answer a question, it can be useful (necessary and unavoidable in my opinion) to bring a sheet of paper and take the time to write down calculations before "clicking".