How do you find the domain of a function?

Posted on Mar 11, 2008 under domain news and reports | 7 Comments

f(x) = sqrt (6 – x)

7 Responses to “How do you find the domain of a function?”

  1. By eliminating invalid x values.
    For f(x) = √(6-x), x ≥ 6, otherwise you're taking the square root of a negative number.

  2. The domain of a function is the set of all valid inputs. So you think about what can't go in the function and then say everything but.
    In the case of a square root, you can't take the square root of a negative number. So think about 6 – x is less than 0. So x would be greater than 6. So the domain is what can go in the fucntion, that is, evernthing less than or equal to 6.
    In the case of a rational function, you can't have a zero denominator. So set the denomnator equal to zero and solve. Then the domain is everything except that.

  3. f(x) = sqrt(6-x)

    Think of x as the input; then f(x) is the output.

    Domain = what you are allowed to use as input.

    Range = what values can be reached by the output.

    When analyzing an equation to find its domain, you have to find impossible situations, for example:
    dividing by zero.
    square roots of negative numbers,
    logarithms of zero or negative numbers,
    etc.

    The domain cannot contain any values for which the equation becomes impossible.

Leave a Reply