SAT Math Multiple Choice Question 919: Answer and Explanation
3. If, what is the domain of f(x)?
- A. All real numbers
- B. All integers except zero
- C. All positive real numbers
- D. All real numbers except zero
Correct Answer: C
Category: Passport to Advanced Math / Functions
Strategic Advice: The domain of a function is the set of x-values for which the function is defined (exists). For basic functions, there are only two rules that can't be broken-the quantity under a square root can't be negative, and the denominator of a fraction can't equal 0.
Getting to the Answer: The square root in the denominator tells you that only numbers greater than or equal to 0 are in the function's domain. However, because the x is in the denominator, it can't be equal to 0. Putting these two restrictions together results in a domain of all real numbers that are strictly greater than 0, or in other words, all positive real numbers, which is (C).