We are asked to determine the intervals where the function is decreasing. To do that we need to remember that a funtion decreases when the output variable decreases as the input variables increases. Graphically, this can be seen where the graph has a negative slope. In this case, the function decreses in the interval:
[tex]\lbrack-2,1\rbrack[/tex]
We use brackets to indicate that the extreme points of the interval are included in the interval.
