To graph the relation, we can plot several points:
When x = 0, y = 4(0) - 1 = -1. So one point is (0, -1).
When x = 1, y = 4(1) - 1 = 3. So another point is (1, 3).
When x = -1, y = 4(-1) - 1 = -5. So another point is (-1, -5).
Plotting these points on a graph, we can see that they lie on a straight line.
[Graph image not available]
Now, let's apply the vertical line test. This test is used to determine if a relation is a function.
If every vertical line intersects the graph at only one point, then the relation is a function.
From the graph, it is clear that every vertical line crosses the graph at a unique point. Therefore, the relation y = 4x - 1 is a function.
So the answer is 1.