Teacher2Teacher Q&A #5112

FOIL Method of multiplying polynomials

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From: Jeanne (for Teacher2Teacher Service)
Date: Nov 16, 2000 at 00:07:44
Subject: Re: FOIL Method of multiplying polynomials

Hello Angela, I use an area model to teach the multiplication of polynomials. We start with (length)(width) = area of a rectangle. Depending upon the class we might start with something as basic as (12)(34). (12)(34) = (10 + 2)(30 + 4) We use the (10 + 2) and the (30 + 4) as the length and width, respectively. __30__+___4__ __30__+___4__ | | | The area of each | | | 10| | | rectangle is computed 10| 300 | 40 | +|______|______| separately. +|______|______| | | | | | | 2| | | 2| 60 | 8 | |______|______| |______|______| The total area is 300 + 40 + 60 + 8 or 408. Applying this to polynomials... __x___+___4__ __x___+___4__ | | | The area of each | | | x| | | rectangle is computed x| x^2 | 4x | +|______|______| separately. +|______|______| | | | | | | 2| | | 2| 2x | 8 | |______|______| |______|______| The total area is x^2 + 4x + 2x + 8 or x^2 + 6x + 8. Hope this helps. -Jeanne, for the T2T service

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