The relativistic sum $w$ of two velocities $u$ and $v$ is given by
$$
\frac{w}{c}=\frac{u / c+v / c}{1+u v / c^{2}}.
$$
if
$$
\frac{v}{c}=\frac{u}{c}=1-\alpha,
$$
where $0 \leq \alpha \leq 1$, find $w / c$ in powers of $\alpha$ through terms in $\alpha^{3}$.