A problem in polynomials to show there are polynomials $f_{1}(x), \cdots f_{k}(x)$ such that $ P(x) = \sum_{j = 1}^{k} (f_{j} (x))^{2}$
Prove that $p \in \mathbb{R}[x]$ can be represented as a sum of squares of polynomials from $\mathbb{R}[x]$