#### Answer

downward;
$2, -6$;
$-6$;
maximum

#### Work Step by Step

RECALL:
The quadratic function $f(x) = a(x-h)^2+k$ has the following properties:
vertex at $(h, k)$
opens downward when $a \lt 0$ and has $f(h)=k$ is its maximum value.
The given quadratic function has:
$h=2, k=-6$
$a=-3$
Thus, the function has:
its vertex at $(2, -6)$;
opens downward;
$f(2)=-6$ is the maximum value of $f$
Therefore, the missing expressions in the given statement (in order) are:
downward;
$2, -6$;
$-6$;
maximum