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Can the method of Finite Differences be used with non-sequential x-values?

1 3 6 10 15 21 28 36 45
24 49 74 99 124 149 174 199 224

Above is a table representing a polynomial function

 May 1, 2014

Best Answer 

 #1
avatar+33654 
+5

Is the first line meant to be the x-values and the second line the y-values? (Actually, the values in each line are sequential, though not with a constant interval in the case of the first line.)

If so, I suggest you first use your method of differences on each line separately to find x in terms of n (the position number of the items : for n = 1, 2, 3, 4 etc    x = 1, 3, 6, 10, etc.

Then eliminate n from the two equations to get x in terms of y.

So, you should find that x = n(n+1)/2  and y = 25n -1.  Eliminate n from these two equations to get x in terms of y.

 

However, I might have misunderstood what you are asking!

 May 1, 2014
 #1
avatar+33654 
+5
Best Answer

Is the first line meant to be the x-values and the second line the y-values? (Actually, the values in each line are sequential, though not with a constant interval in the case of the first line.)

If so, I suggest you first use your method of differences on each line separately to find x in terms of n (the position number of the items : for n = 1, 2, 3, 4 etc    x = 1, 3, 6, 10, etc.

Then eliminate n from the two equations to get x in terms of y.

So, you should find that x = n(n+1)/2  and y = 25n -1.  Eliminate n from these two equations to get x in terms of y.

 

However, I might have misunderstood what you are asking!

Alan May 1, 2014

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