Basis functions for polynomial

Somefantastik
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Homework Statement


For I = [a,b], define: P3(I) = {v: v is a polynomial of degree ≤ 3 on I, i.e., v has the form v(x) = a3x3 + a2x2 + a1x + a0}. How to show v is uniquely determined by v(a), v'(a), v(b), v'(b).


Homework Equations





The Attempt at a Solution



I'm not exactly sure what I'm being asked to do here. I don't need the problem solved, just a nudge in the right direction.
 
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I guess I = [a,b] just stands for an interval of real numbers?

I also guess that you are allowed to assume that multiplication and addition of given real numbers always produces a unique real number?

Then your four given coefficients ai uniquely determine P.

So it seems you are being asked to prove that v(a), v'(a) etc. uniquely determine the ai .
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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