Function y=ax^2+bx+c

Guest:

Ball falls down from 20 m height. It's height differences are h=-4,9t^2+20 I need to build a graph. From where do I start?

H is height and T is time
so should I do this?
t 1 2 3 4
h -4,9*1^2+20 to build a graph?

Yes you can do this
t is the horizontal axis and h is the vertical axis.

start with t=0, h=20
then you can sub in other vaues of t to get more points.

It might also be useful to solve the equation for t for h=0. That will tell you how long before the ball fits the ground.
This will be an end point of the graph.

You may also recognise this function as a concave down parabola, with the vertex at (0,20) [first quadrant only, of course, for this problem]