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Check it outSolving Quadratic Equations by Factoring  Problem 3 9,175 views
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
Here’s a problem that I want to solve by factoring. What I’m going to be doing is looking for two numbers that multiply to +9 and add up to +6. That’s not too hard I know that’s going to be x plus 3 and x plus 3.
Now this is kind of strange because what I have is x plus 3 squared equal to 0 and I need to set each factor equal to 0 in order to solve for x but both the factors are the same that’s okay. What I have going on here is a problem where I have only one solution. The only solution comes from setting x plus 3 equals 0 because both my factors are the same. What this means is the only number that will make this statement true is the value 3.
Let’s just check and make sure that 3 does indeed work. 3 times itself is 9 plus, 6 times 3 plus 9 if that’s equal to 0 I’m a happy camper. 9 take away 18 plus 9 good, it does indeed equal to 0.
So this is a strange problem because I have only one solution, the way you might recognize this is if you are good at spotting perfect square trinomials. This is a perfect square trinomial because it comes from a binomial times itself. Anytime you have a perfect square trinomial it means you are only going to have one x solution.
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Sample Problems (15)
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Solving Quadratic Equations by Factoring
Problem 1 12,628 viewsSolve by factoring:
x² + 4x = 0 
Solving Quadratic Equations by Factoring
Problem 2 9,913 viewsSolve by factoring:
x² + 2x = 15 
Solving Quadratic Equations by Factoring
Problem 3 9,174 viewsSolve by factoring:
x² + 6x + 9 = 0 
Solving Quadratic Equations by Factoring
Problem 4 8,851 viewsSolve by factoring:
3x² − 18x = 27 
Solving Quadratic Equations by Factoring
Problem 5 559 views 
Solving Quadratic Equations by Factoring
Problem 6 511 views 
Solving Quadratic Equations by Factoring
Problem 7 444 views 
Solving Quadratic Equations by Factoring
Problem 8 433 views 
Solving Quadratic Equations by Factoring
Problem 9 446 views 
Solving Quadratic Equations by Factoring
Problem 10 437 views 
Solving Quadratic Equations by Factoring
Problem 11 389 views 
Solving Quadratic Equations by Factoring
Problem 12 417 views 
Solving Quadratic Equations by Factoring
Problem 13 386 views 
Solving Quadratic Equations by Factoring
Problem 14 424 views 
Solving Quadratic Equations by Factoring
Problem 15 406 views
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