Answer:
The answer is: 0
Step-by-step explanation:
Let's imagine we have two sets of values. In math, function is an equation, or, better said, a relation that connects values from sets in a manner that one value from one set corresponds to only one value from the other. Values from the first set are referred to as "x" while the values from other set are "f(x)". So, for each x there is only one f(x). Here, we have two sets of numbers and since they are organized in a table, for each number in a square of a column there is a corresponding number in the next column.
x: f(x):
-5 => 4
-1 => 0
6 => -1
9 => -3
That means that if x=-5, f(-5)=4. Similarly, if x=-1, f(-1)=0.