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Question 396635:  Hello, 
What about if I know some values for x and y and I want the function? Example: I want to build a curve, arc segment; and I know that when: 
x=1 y=2 
x=2 y=1 
We could say y = 3-x, but that isn't a curve. 
So, how do I get the curve? 
Thanks for the attention! 
 Answer by Alan3354(69443)      (Show Source): 
You can  put this solution on YOUR website! With only 2 points, you can put a unique straight line thru them. 
If it's any type of curve you have to specify what type curve. 
eg, if it's a circle and one point is the center, then that's sufficient. 
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But if it's 2 points on the circle, then an infinite # of circles can be made to pass thru them. 
The same for parabolas, hyperbolas, and all conic sections. 
If you have 3 points and the type of conic section, that's sufficient. 
If you have 5 points and know that it's a conic section, that's sufficient. 
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A general polynomial can be found to pass thru any number of points. 
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