Teacher2Teacher Q&A #18119

Teachers' Lounge Discussion: "Bottoms up" as a method to factor trinomials

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From: Rochelle Adler Effron

To: Teacher2Teacher Public Discussion
Date: 2010060322:35:49
Subject: Re: "Bottoms up" as a method to factor trinomials

I just happened upon this discussion, so maybe no one cares any more, but I think the "Bottoms Up" name comes from the procedure of bringing the denominator (BOTTOM) of the fraction which will not simplify to an integer in the binomial (x+2/3) UP to be the coefficient of the variable (3x+2). Personally, I don't like this method; there is no logical feel for why it works (the proof requires a change of variable which is way beyond most of the algebra students who are learning factoring) and my experience is that when students actually have to use factoring to solve a problem, they forget to divide by the coefficient a after factoring the revised x^2 + bx + ac expression and get wrong answers.

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