The choices to pic from are(1.9,-0,7), (0,infinite)(-infinite, -3.1) (-3,infinite)(-infinite,-0.7) (0, infinite)(-0.7,0)(0,-3.1) (-3,infinite)(-3.1,-3)

Decreasing interval is when the graph is going down as x is increasing
It is decreasing from - infinity to -.667 and then from 0 to infinity
(-infinity,-0.7) (0, infinity)