Step 1:

The equation $\"\"$

To determine whether the equation $\"\"$ ,which defines the quadratic expression is a function.

The equation tells us to take an input $\"\"$ .

For any input of $\"\"$ then we get only one out put for $\"\"$ .

Step 2:

An input $\"\"$

Substitute $\"\"$ in $\"\"$

$\"\"$

An input $\"\"$

Substitute $\"\"$ in $\"\"$

$\"\"$

Solution : The equation defines $\"\"$ as a function of x.