Is this graph a function or not a function

In the graph of a circle, we can easily draw a straight vertical line passing through its center. This will hit the top and the bottom of the shape. Since this line hits two points, a circle's graph is not a function. We can also observe the equation of a circle.

(1,4) is on graph of f(x)

f(1) = 4

so 1/4 f(x)

1/4 f(1)

1/4. ×4

1

so point for function 1/4. f(x) is (1,1)