
f(x) has to be close to -1 when x is close to -3, and so f(x) is increasing when x increases, and there are no numbers from -1 to ∞ that there is no f(x) value. In the first piece of the function
f(x) ranges from -1 to 4 and the second piece from 0 to ∞ so. The ranges had to overlap since it's not defined at x = 2.