What is the domain and range of f (x) = x

The domain is all real numbers. The range is all real numbers.

The only thing that restricts the domain of an equation is when we are dividing by 0 or have a negative under the square root. Since there is no division sign or square root, we no there is no domain restrictions.

Also, since the range is the exact same as the domain (since f (x) is equal to x), we know the range also have no restrictions.