To determine on what open intervals the function $g(x)$ is decreasing from the graph, we need to look for the sections where the graph has a negative slope (i.e., where the graph is sloping downwards).

From the graph:

1. The function decreases between two specific points:
   • Between the peak at point $A$ (approximately $x = -2$) and the trough at point $B$ (approximately $x = 1$).
   • This gives the interval where $g(x)$ is decreasing as $(-2, 1)$.

So, the function is decreasing on the interval:

$(-2, 1)$

Would you like further details or have any questions on this? Here are 5 related questions to expand your understanding:

1. What is the definition of an increasing interval on a graph?
2. How can the first derivative help identify increasing and decreasing intervals?
3. How would you find the local minima and maxima of $g(x)$?
4. How do concavity and points of inflection relate to increasing and decreasing behavior?
5. How does this information about decreasing intervals help in understanding the overall behavior of a function?

Tip: To confirm decreasing intervals algebraically, the derivative $g'(x)$ should be negative within those intervals.