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Introduction to Rational Functions  Problem 2
Alissa Fong
Alissa Fong
MA, Stanford University
Teaching in the San Francisco Bay Area
Alissa is currently a teacher in the San Francisco Bay Area and Brightstorm users love her clear, concise explanations of tough concepts
I’m going to look at this function and try to find the domain. Remember the domain is the set of all possible input or x values. In order to find the domain I’m going to think about what we call the excluded value. An excluded value would be any value of x that would make this function undefined. A function is undefined if the denominator or the bottom is equal to 0.
So my excluded value is going to be the value x equals 3. That’s an excluded value because if x were a 3 this denominator would be 0 and that’s bad news. So when you ask me to find the domain I would say x is all real numbers except for 3. x is all reals, I guess I’m just going to say the domain is all real numbers, you can abbreviate that with ‘all reals' except 3, because 3 is what we call an the excluded value. When you guys start making the graphs of these you'll see when it shows up in an asymptote. For now it’s advised to say the domain is any value, any real number except for 3 because if x were equal to 3, that fraction would be undefined.
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Alissa Fong
M.A. in Secondary Mathematics, Stanford University
B.S., Stanford University
Alissa has a quirky sense of humor and a relatable personality that make it easy for students to pay attention and understand the material. She has all the math tips and tricks students are looking for.
Your tutorials are good and you have a personality as well. I hope you have more advanced college level stuff, because I like the way you teach.”
Thanks alot for such great lectures... I never found learning this easier ever before... keep up the great work.... :)”
You seem so kind, it's awesome. Easier to learn from people who seem to be rooting for ya!' thanks”
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Introduction to Rational Functions
Problem 1 4,972 viewsFind the domain of
f(x) = 4 x 
Introduction to Rational Functions
Problem 2 4,012 viewsFind the domain of
f(x) = 4 x − 3 
Introduction to Rational Functions
Problem 3 3,542 viewsFind the domain of
f(x) = 4 2x² + 5x + 3 
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Problem 4 673 views 
Introduction to Rational Functions
Problem 5 506 views 
Introduction to Rational Functions
Problem 6 577 views 
Introduction to Rational Functions
Problem 7 525 views 
Introduction to Rational Functions
Problem 8 495 views
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