Find the equation of the parabolay=ax² +bx+cthat contains the points (1, -2), (2, 0), and (4, 22).

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- May 10th 2009, 12:33 PMbearej50Equation of a ParabolaFind the equation of the parabola
*y*=*ax*² +*bx*+*c*that contains the points (1, -2), (2, 0), and (4, 22).

- May 10th 2009, 12:36 PMMush
Plug in the points and you'll get three equations.

You can solve this system of equations in a number of ways. I recommend setting up a matrix.

So let's write that as . We want to find x, hence:

And you know how to calculate the inverse of a 3x3 matrix hopefully! - May 10th 2009, 01:18 PMbearej50
I was taught a different way. Subtract the equations from one another.

I got a = 13/5, b = -23/5, and c = 0. Is this right? - May 10th 2009, 01:24 PMMush