The domain of a function is the set of values of the independent variable (x) for which the function is defined.

There are two common mathematical operations that are undefined: square root of a negative number and division by zero.

Because a square root cannot successfully act on a negative number, the domain of f(x) = squareroot of x is all real numbers x such that x is greater than or equal to 0 . In set notation, this would be written domain 3 .

Division by zero is undefined; therefore values for x that produce a zero denominator are excluded from the domain. For instance, the function domain 3 has a domain of all real numbers except domain 4 and domain 5 . In set notation, this would be written domain6 .