# How do you find an equation from a quadratic graph?

+1 vote

I am trying to figure out the equation to a quadratic graph. I made a Google Document to show you what im doing, the only thing I didn't put is the graph. Could anyone please help, and tell me how to do it?

The first step in doing so would be to graph it. If you are allowed to use a graphing caclculator this would be extremely easy to do.  You would just enter the points on the list, and find the equation for the quadratic function and you would get your answer.

If you are not allowed to use a calculator to solve then here is some additional help:

1. note the quadratic equation comes in the form y=ax^2+bx+c

2. you have several sets of points, so plug in the points into the equation for the x and the y.

For example: plugging in points (-1,6) would result in 6=a(-1)^2+b(-1)+c

then you might plug in points (0,3) to get 3=a(0)^2+b(0)+c,

so now you know that c=3.

continue plugging in points until you are able to solve for the variables 'a' and 'b'.

answered Jan 7, 2012 by ~Expert~ (3,856 points)
edited Jan 7, 2012

+1 vote