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Question 322835: Find the domain of the function.
f(x)=sqrt(18-x)
Answer by rapaljer(4671)   (Show Source):
You can put this solution on YOUR website! f(x) = 
The restriction in this case is that in the real numbers, you cannot have a negative within a square root sign. This means that
Solve for x:
Divide both sides by -1, which REVERSES the inequality sign.
In interval notation: (-inf,18]
For additional help with FUNCTIONS,DOMAIN, AND RANGE, please see my own website. Click on my tutor name "rapaljer" anywhere in algebra.com. There, click on my website. From my Homepage, look for the link near the top of the page "Basic, Intermediate, and College Algebra: One Step at a Time." Then click on either "Intermediate Algebra" or "College Algebra". In Intermediate Algebra, see "Chapter 5", "Section 5.06." OR, look in "College Algebra" in "Chapter 2" for the topic of Functions, Domain and Range. There you will find my own non-traditional explanations, examples, exercises, and answers to ALL the exercises, and solutions to many of the problems on the "MATH IN LIVING COLOR" pages that go with these explanations.
See also the FREE video from my own classes a few years before I retired! From my Homepage, look for the link "Rapalje Videos in Living Color". Then look for either "Intermediate Algebra" or "College Algebra", and choose the "Functions, Domain, and Range" topic. You may need to download RealPlayer if you do not have it, but this is a FREE download. I hope you will find my explanations easier to understand than the traditional explanations in your expensive textbooks!!
Dr. Robert J. Rapalje, Retired
Seminole State College of Florida
Altamonte Springs Campus
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