Take a look at the graph starting from the left. You’ll see that on the horizontal line, the graph starts at -4 then starts to go downward until it gets to -2 and it starts going up after that so your first interval is (-4, -2). The line increases from -2 to 2 and then it starts sliding downward again from 2 to 4 so your second decreasing interval is (2, 4).
