Answer:
Point (0,0) is a local minimum and point (8,4) is a local maximum.
The function is incrasing for all

The function is decreasing for all

Explanation:
Plot the graph of the function
(see attached diagram for details).
A local extremum is a local maximum or a local minimum.
From the graph of the function, you can see that point (0,0) is a local minimum and point (8,4) is a local maximum.
The function is incrasing for all

The function is decreasing for all
