# Proving that a set is a set of generators

1. Sep 1, 2013

1. The problem statement, all variables and given/known data
I want to show that the set
$$<1,x,x^2,\cdots ,x^n>$$
forms a basis of the space
$$P_{n}$$
where
$$P_{n}$$ contains all polynomial functions up to fixed degree n.

3. The attempt at a solution
I have already shown that the set
$$<1,x,x^2,\cdots ,x^n>$$
is linearly independent and now I want to show that this set is a set of generators for $$P_{n}.$$

Take any
$$f\in P_{n}.$$ Let
$$<\alpha_{0},...,\alpha_{n}>$$
represent the coefficients of $$f.$$ Then since
$$\alpha_{0}\cdot 1=\alpha_{0},...,\alpha_{n}\cdot x^{n}=\alpha_{n}x^{n}$$
$$\alpha_{0}+\cdots+\alpha_{n}x^{n}=f.$$

Is that correct or am I missing something? Thanks!

2. Sep 1, 2013

### tiny-tim

(use # instead of \$ and it won't start a new line every time! )

Yes, that looks fine, except I think you can shorten it a little:

you can say that by definition, any f in Pn is of the form $\alpha_{0}+\cdots+\alpha_{n}x^{n}$

3. Sep 1, 2013