The basic expression of quadratic function is y=ax? +bx+c(a≠0), the highest degree of quadratic function must be quadratic, and the image of quadratic function is a parabola whose symmetry axis is parallel or coincident with 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.
Properties of quadratic function:
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 smaller |a|, the larger the opening of parabola; The larger the |a|, the smaller 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