Let $$f(x) = x^2 + 6 x - 7.$$
(A) Use interval notation to indicate where $f(x)$ is increasing.

Note: When using interval notation in WeBWorK, remember that:
(i) You use 'I' for $\infty$ and '-I' for $-\infty$.
(ii) '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 =