Vertical Line Test :

A curve in the $\"\"$ plane is the graph of a function of $\"\"$ if and only if no vertical line intersects the curve more than once.

Observe the graph.

Draw a vertical line along the $\"\"$ axis, the line touches the curve only once.

The graph of the function passes the vertical line test.

Hence, by the definition of vertical line test, the graph is a function of $\"\"$ .

The domain is the set of all values of $\"\"$ on the curve.

The curve is defined for $\"\"$ .

The domain of the function is $\"\"$ .

The range is the set of all values of $\"\"$ on the curve.

The curve takes all the value from $\"\"$ to $\"\"$ .

The range of the function is $\"\"$ .

Yes, graph is a function of $\"\"$ .

The domain and range of the function is $\"\"$ and $\"\"$ .