Chapter 1 - Functions and Limits - 1.1 Four Ways to Represent a Function - 1.1 Exercises - Page 21: 37

The Domain is $0\leq p \leq4$

$F(p) = \sqrt {2-\sqrt p}$ first of all because $\sqrt p$, $p\geq0$ and becuase $\sqrt {2-\sqrt p}$ $2-\sqrt p \geq0$ $2 \geq \sqrt p$ $4\geq p$ lets add both together, and the union is: The Domain is $0\leq p \leq4$