Given:-
The curve is given in the graph.
To find:-
The intervals in which the graph is decreasing.
The graph which has been given has an interval from,

So now its required to find the decreasing interval in the graph.
Decreasing interval is known as in which certain ranges the curve makes a bend direction towards the downwards.
so from the interval ranges from (-9,2) to (9,6). The bend towards downwards are in the range interval,

Not only the interval ranges from (-9,2) to (-4,-2) but also,

So the total interval which has decreasing interval in the given curve are (-9,2) to (-4,-2) and also (-1,6) to (4,3).