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Simplifying Rational Functions with Factoring and GCFs  Concept
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
Simplifying rational expressions combines everything learned about factoring common factors and polynomials. When simplifying rational functions, factor the numerator and denominator into terms multiplying each other and look for equivalents of one (something divided by itself). Include parenthesis around any expression with a "+" or "" and if all terms cancel in the numerator, there is still a one there.
A lot of times you're going to be given a rational expression and asked to simplify it. Simplify if means you want to eliminate any factors that are the same on top and bottom of the fraction. So here are some things to keep in mind, first thing make sure you factor everything completely and then cross out any factors that are exactly the same on top and bottom. They have to be exactly the same, watch out for what we call opposite factors, there'll be something like this, if you have x minus 2 and 2 take away x, those are really close they're what we call opposite because this guy is actually that guy multiplied by negative 1. Let me prove it to you, if I were to factor out a negative 1 from this second factor parentheses grouping I would see negative 1 times negative 2 plus x which is the same thing a negative 1 times x minus 2.
Now you can see that those are what we call opposite factors, this guy just got multiplied by negative one. That's something that'll help you, when you're simplifying rational expressions. So again the most important thing is to factor everything completely and only cross out factors that are the same in top and bottom. That means it has to be in it's multiplied form, you can't cross out something like this, let me show you. If I had x plus 2 divided by 2 a lot of students would be tempted to cancel out those 2s but in fact that's not a factor. A factor means things have to be multiplied so on top that's not a factor like 2 is not a factor of this x plus 2 business. I could cancel out if I had instead of that, if I had 2x over 2 now those 2's are eligible to be reduced because 2 over 2 is the same thing as 1. So keep that in mind when you're simplifying rational expressions. Factor everything and then only cross out factors that are exactly the same on the top and bottom of your fraction.
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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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Sample Problems (15)
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Simplifying Rational Functions with Factoring and GCFs
Problem 1 5,779 viewsSimplify and find any excluded values.
4x³ 16x 
Simplifying Rational Functions with Factoring and GCFs
Problem 2 5,205 viewsSimplify and find any excluded values.
18x³ 6x + 12 
Simplifying Rational Functions with Factoring and GCFs
Problem 3 4,739 viewsSimplify and find any excluded values.
8m + 16 2m² + 5m + 2 
Simplifying Rational Functions with Factoring and GCFs
Problem 4 4,270 viewsSimplify and find any excluded values.
9 − 3x 3x² − 9 − 6x 
Simplifying Rational Functions with Factoring and GCFs
Problem 5 589 views 
Simplifying Rational Functions with Factoring and GCFs
Problem 6 568 views 
Simplifying Rational Functions with Factoring and GCFs
Problem 7 531 views 
Simplifying Rational Functions with Factoring and GCFs
Problem 8 558 views 
Simplifying Rational Functions with Factoring and GCFs
Problem 9 449 views 
Simplifying Rational Functions with Factoring and GCFs
Problem 10 507 views 
Simplifying Rational Functions with Factoring and GCFs
Problem 11 624 views 
Simplifying Rational Functions with Factoring and GCFs
Problem 12 497 views 
Simplifying Rational Functions with Factoring and GCFs
Problem 13 518 views 
Simplifying Rational Functions with Factoring and GCFs
Problem 14 565 views 
Simplifying Rational Functions with Factoring and GCFs
Problem 15 508 views
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