Let \(f : [0, 1] \to \mathbb {R}\) be a continuous function and define a signed measure \(\mu \) on the Lebesgue measurable subsets of \([0, 1]\) by
\[ \mu (E) = \int _{E} f\,dm \]
where \(m\) is Lebesgue measure. Suppose that for all \(n = 0, 1, 2, 3, \ldots \)
\[ \int _{[0,1]} x^{n}\,d\mu = 0 \]
Prove that \(\mu = 0\).