Derivation process of the intersection of quadratic function: If (x 1, 0) and (x 2, 0) are two intersections of quadratic function y = ax 2+bx+c, then x 1, x2 must be the unary quadratic equation ax 2+bx+c = 0 (a ≠. We call y=a(x-x 1)(x-x2) the intersection of quadratic functions.

Intersection of quadratic function, mathematical terminology, middle school mathematics in application field, intersection point: y=a(x-x 1)(x-x2), limited to parabolas with intersection points A (X 1, 0) and B (X2, 0) with X axis. Draw two mutually perpendicular number axes with a common origin on the plane to form a plane rectangular coordinate system.

Among them, the horizontal axis is called X axis or horizontal axis, and the right direction is the positive direction; The vertical axis is called Y axis or vertical axis, and the orientation is positive; The intersection o of the two axes (that is, the common * * *) is called the origin of the rectangular coordinate system; The plane on which the rectangular coordinate system is established is called the coordinate plane.

In order to describe the position of a point in the coordinate plane conveniently, the coordinate plane is divided into four parts, namely the first quadrant, the second quadrant, the third quadrant and the fourth quadrant. The basic expression of quadratic function is y=ax? +bx+c(a≠0).

The highest order of a quadratic function must be quadratic, and the image of a quadratic function is a parabola whose symmetry axis is parallel or coincident with the Y axis. The expression of quadratic function is y=ax? +bx+c (and a≠0), which is defined as quadratic polynomial (or monomial). If the value of y is equal to zero, a quadratic equation can be obtained. The solution of this equation is called the root of the equation or the zero of the function.

Five-point method:

Five-point sketch, also known as five-point drawing, is a common drawing method in quadratic function. Note: Although it is a sketch, it is by no means a sketch. Five points in the five-point sketch method are extremely important, namely, the vertex, the intersection with the X axis, the intersection with the Y axis and their symmetrical points about the axis of symmetry.

This method is also used to determine the image of Ps formal examination. But the requirement of the formal examination is to list the grids, take X and Y, and then determine the overall image. You can use the five-point method in the formal examination.