Find $x(t): \int_0^1 f(t)\,\mathrm dt = 0$ and $\int_0^1 x(t)f(t)\,\mathrm dt = 0$?

Question

Exercise: the projection of function $t^2$ over $\displaystyle M=\left\{f(t)\Bigg|\int_0^1f(t)\,\mathrm dt=0\right\}$.

I get stuck when finding all the function $x(t) \in L^2([0,1],\mathbb{R})$ such that $\langle x(t),t^2\rangle=0$. Any help would be appreciated.