Not all points have the same distance from this point, but the distance from any point to this line is the same, and the distance from different points to this point is generally different, for example, y=0.25x? This is (0, 1), and the straight line is y=- 1.
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.
Extended data:
The image of quadratic function is a parabola, but parabola is not necessarily a quadratic function. The parabola of the opening up or down is a quadratic function. Parabola is an axisymmetric figure.
The only intersection of the symmetry axis and the parabola is the vertex p of the parabola. Especially when b=0, the symmetry axis of the parabola is the Y axis (that is, the straight line x=0).
Quadratic coefficient a determines the opening direction and size of parabola. When a>0, the parabolic opening is upward; When a<0, the parabolic opening is downward. The larger |a|, the smaller the opening of parabola; The smaller the |a|, the larger the opening of the parabola.
Both linear coefficient b and quadratic coefficient a*** determine the position of the axis of symmetry. When A and B have the same number (ab>0), the symmetry axis is on the left side of Y axis; When a and b have different numbers (i.e. AB
Baidu Encyclopedia-Quadratic Function