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Multiplying Polynomials: Special Cases  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
Solving rational equations is substantially easier with like denominators. When solving rational equations, first multiply every term in the equation by the common denominator so the equation is "cleared" of fractions. Next, use an appropriate technique for solving for the variable.
When you're multiplying binomials, there's a couple things that we call special cases.
One special case is when you get a perfect square trinomial. A perfect square trinomial is the result of squaring a binomial, ulet me show you what that looks like. If I have a binomial like a+b and I square it, which means multiplying it by itself, so you could write it like this also, my answer always looks like a squared plus 2ab plus b squared always always always when I take a binomial and I square it my answer looks like this we call this a perfect square trinomial because took binomial and squared it. That's one special products that you're going to see.
Another one you're going to see that's one of my personal favorites is if I do a product like a+b multiplied by ab. If I would FOIL or do a rectangle my inner and outer terms would be eliminated they'll be added as inverses. Here's what I'm talking about, b times a my inners, and negative b times a my outers are additive inverses they cancel each other out my final answer for this kind of product always looks like a squared take away b squared. That's another one of my personal favorites.
These are called special cases and you're going to see a lot of problems that have this type of answer only not going to always use the letters a and b. It might be like x and y or 2x and y or 2x and 4 something like that, but when you have these kinds of patterns in your original problem like a squared binomial or a plus and a minus where the terms are the same otherwise you're going to get these special results, so keep that in minds when you're working through your homework when you're multiplying binomials and trinomials.
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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.
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Sample Problems (5)
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Multiplying Polynomials: Special Cases
Problem 1 5,012 viewsMultiply:
(3a + 2b)² 
Multiplying Polynomials: Special Cases
Problem 2 4,238 viewsMultiply:
(3a − 2b)(3a + 2b) 
Multiplying Polynomials: Special Cases
Problem 3 3,967 viewsMultiply:
(x − 2)³ 
Multiplying Polynomials: Special Cases
Problem 4 635 views 
Multiplying Polynomials: Special Cases
Problem 5 599 views
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Violet · 8 months, 3 weeks ago
I would also like to know how you can take a trinomial and reverse it back to (a+b)(ab) or (a+b)^2. something similar or exactly like that :)