The concept of quadratic function Definition: a function of shape is called a quadratic function of X General form: Conditions:

The concept of quadratic function Definition: a function of shape is called a quadratic function of X General form: Conditions:

General form: y = ax & sup2; + BX + C
Condition: a ≠ 0
If a = 0, the equation represents a linear function, and the image is a straight line
Only when a ≠ 0, the equation represents quadratic function and the image is parabola
Quadratic functions can also be expressed in other forms
For example, y = a (X-H) & sup2; + K (a ≠ 0) so that the vertex of the parabola is (h, K)
Or y = a (x-x1) (x-x2) (a ≠ 0) so that the two intersections of the parabola and the X axis are (x1,0) and (x2,0)
Of course, the number of intersection points of parabola and X axis may be 0, 1 or 2, which can be judged by discriminant