Let $$f(x) = -9 - 21 x + 12 x^2 - x^3.$$
(A) Use interval notation to indicate where $f(x)$ is increasing.

Note: Use 'INF' for $\infty$, '-INF' for $-\infty$, and use 'U' for the union symbol.
Increasing:

(B) Use interval notation to indicate where $f(x)$ is decreasing.

Decreasing:

(C) Find the average of the $x$ values of all local maxima of $f$.
Note: If there are no local maxima, enter -1000.

Average of $x$ values =

(D) Find the average of the $x$ values of all local minima of $f$.
Note: If there are no local minima, enter -1000.

Average of $x$ values =

(E) Use the preceding information to sketch a graph of $f$. When you're finished, enter a "1" in the box below.

Graph Complete: