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Factoring Trinomials, a = 1  Problem 3
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
This problem I have a trinomial where my b value is negative but c is positive. Keep in mind this is the product of my two values, this is their sum. I’m looking for two numbers that multiply to a positive answer but add up to a negative answer. That means I’m looking for two negative values. A negative times a negative is a positive and when I add them up I also have a negative answer, so now I need to think of what 2 numbers multiply to 10, add up to 7 and there both going to be negative numbers.
Well things that multiply to 10 are either 1 or 10. That’s not going to work because they don’t ever add up to anything close to 7. Or 5 and 2: in our case 5 and 2, because is need them to add up to a negative number and multiply to a positive number. There they are. That’s my factored form.
I’m going to go through and FOIL just to check; firsts, outers, inners, lasts. And I can already see in my brain when I combine those middle terms I will have 7. That’s how I know it's right. I just wanted to show you guys one of the tricks of how to approach these problems. It gets a lot trickier when you don’t have a 1, if you have like a 2 or something there. So it’s important that you spend time now looking for patterns when you have positives and negatives showing up in your coefficients.
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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 (11)
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Factoring Trinomials, a = 1
Problem 1 13,834 viewsFactor:
x² + 12x + 20 
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Problem 2 9,481 viewsFactor:
p² + 3p − 10 
Factoring Trinomials, a = 1
Problem 3 8,343 viewsFactor:
m² − 7m + 10 
Factoring Trinomials, a = 1
Problem 4 7,453 viewsFactor:
x² + 9x − 20 
Factoring Trinomials, a = 1
Problem 5 1,235 views 
Factoring Trinomials, a = 1
Problem 6 918 views 
Factoring Trinomials, a = 1
Problem 7 902 views 
Factoring Trinomials, a = 1
Problem 8 874 views 
Factoring Trinomials, a = 1
Problem 9 1,295 views 
Factoring Trinomials, a = 1
Problem 10 809 views 
Factoring Trinomials, a = 1
Problem 11 972 views
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