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Find a quadratic model for (-1,1), (1,1), (3,9)

User IUnknown
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Answer by josmiceli(16155) (Show Source):You can put this solution on YOUR website!
I can call the points (x1,y1), (x2,y2), and (x3,y3)



Now, plugging in the actual x's and y's



The general form for a quadratic is

Now I can write

(1)
and

(2)
and

(3)
This is 3 equations and
3 unknowns, so it's solvable
Add (1) and (2) to get




Substitute this in (3)





Now substitute and back into (2)
(2)
(2)
Now solve for , then do more substitutions to get and








The solution is

User Shuman
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