Given data:
The graph of the function.
If the first derivative of the function is negative the function is decreasing in nature. From the given graph the slope or firt derivative is negative when x belongs to the interval (-∞, -2).
The slope of the graph is positive when x belongs to the interval (2,∞).
Thus, in the interval (-∞, -2) the function is decreasing and in the interval (2,∞) the function is increasing.