Given:
Function is:

Find-:
Check the value of "x" for the function is valid.
Explanation-:
The function is:

Solve the function for "x."

When the value of "x" is greater and equal to 4, the function is True.
Check for given "x" is:

The above value of "x" is less than four; the function is False.
The value of "x" at -2, 0 and 2 are function is False.

The value of "x" at 4 and 6 are function is True.