Which absolute value function defines this graph?

y = -3|x|
y = |x|
x = |y|
y = 3|x|
x = 3|y|
looks like a v with point on 0

If you describe the graph as a V with its vertex point on (0,0), then you are either describing the graph of y = |x| or y = 3|x|. The only difference is that the coordinates of y=3|x| is multiplied thrice the coordinates of y=|x|. In other words, this graph is thrice wider than the y=|x|.

Furthermore, y = -3|x| is a downward V, and
x = |y| and x = 3|y| looks like a V rotated side-ward,

The vertex of the quadratic function is (1.5, -.75)