Solution
= Solution
For $W=\max\{U,V\}$ and $0\le w\le1$, <independence> gives the <cumulative distribution function>
$$
F_W(w)=\mathbb P(U\le w,V\le w)=w^2.
$$
The <cumulative distribution function> is zero below $0$ and one above $1$. Differentiating on the interior gives
$$
\boxed{f_W(w)=2w\quad(0<w<1),\qquad f_W(w)=0\quad\text{otherwise},}
$$
up to irrelevant endpoint values. There are no endpoint atoms. This maximum is an <order statistic>.