2. For example, many test questions can be compiled by substituting a linear equation into a quadratic equation, and then using the discriminant of roots, the formula for finding roots, the relationship between roots and coefficients, and the formula for the distance between two points. These questions examine the basic methods of analytic geometry. There are many general methods in high school mathematics, such as the general methods of finding the maximum value of quadratic function in closed interval: formula, drawing and classified discussion.