General Form of Quadratic Functions 二次函數的圖像：一般式

Which one, a, b or c, equals to the y-intercept of the quadratic graph? If we change the values of the other two, will the y-intercept of the graph changes?

Write down any three quadratic functions such that their y-intercepts are all 2.

Which one, a, b or c, relates to the direction of opening of the quadratic graph? How?

Write down any three quadratic functions such that their directions of opening are all downwards.

What is the relationship between the coordinates of vertex of a quadratic graph and the equation of its axis of symmetry?

What is the relationship between the x-intercept(s) (if any) of a quadratic graph and the equation of its axis of symmetry?