A book I am reading demonstrates how $5n^3 + 2n^2 + 22n + 6 = O(n^3)$, which I believe is true. After all, there exists a value $c$ for which $cn^3$ is always greater than $5n^3 + 2n^2 + 22n + 6$ for all $n$ greater than or equal to some value $n_0$.
However, the book then casually notes that $c = 5$ and $n_0 = 10$. Where did these values come from? What algebraic calculations were done (if any) to derive the $c$ and $n_0$ values?