Find the equation of a parabola that passes through the points (-2,3), (-1,1) and (1,9). Any help would be great;so confused right now. Stuck on this for over a hour now!

- Jun 28th 2010, 05:06 PMdillysmommaFinding equation of parabola passing through three known points.
**Find the equation of a parabola that passes through the points (-2,3), (-1,1) and (1,9). Any help would be great;so confused right now. Stuck on this for over a hour now!**

- Jun 28th 2010, 05:25 PMpickslides
Well the equation of a parabola is $\displaystyle y = ax^2+bx+c$

substitute your points in one at a time then solve remaining system of equations.

Here's a kicker.

$\displaystyle (-2,3): 3 = a(-2)^2+b(-2)+c \implies 3 = 4a-2b+c$

Now you have a go. - Jun 28th 2010, 05:37 PMdillysmomma
okay ill try some more now. ty

- Jun 28th 2010, 06:25 PMChris11
If you substitute the values into the general quadratic equation, then you get a linear system, which you can solve with substitution methodes.