Can somebody teach what quadratic function is?

A quadratic function is one of the form f(X)=ax^2+bx +c,where a,b and c are numbers with 'a' not equal to zero.
The graph of a quadratic function is a curve called a parabola. Parabola may open upward or downward and vary in 'width' or 'steepness' , but all have the basic "U" shape.
All parabolas are symmetric with respect to a line called the axis of symmetry. A parabola intersects its axis of symmetry at a point called the vertex of the parabola.
You know that the two points determine a line. This means that if you are given any two points in the plane,then there is one and only one line that contains both points.

Hope this was helpful...!!!

The answer is 225 miles per 4.5 hours. hope this ; )