Answer
$g(x)=-\sqrt {x-3}-2$
Work Step by Step
Let the final function be $g(x)$.
Start from $f(x)=\sqrt x$
(1) Reflect about the x-axis gives $-f(x)$
(2) Shift right 3 units gives $-f(x-3)$
(3) Shift down 2 units gives $-f(x-3)-2$.
Thus the function is $g(x)=-\sqrt {x-3}-2$.