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Q&A #849

Teachers' Lounge Discussion: Factoring the sum and difference of two cubes

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From: Roger

To: Teacher2Teacher Public Discussion
Date: 2007120512:03:20
Subject: teaching the factoring sum or difference of cubes

Factor: x^3 + 8 1) There are two factors: one is a binomial, the other a trinomial. ( ____ ____ )( ___ ___ ___ ) 2) The binomial is the cube root of the first term: x the cube root of the second term 2 separated by the same sign as the original ( x + 2 )( ) 3) The first term of trinomial is the square of the first term in the binomial x^2 The last term of the trinomial is the square of the second term in the binomial +4 [This term is always positive because any real number squared is positive.] ( x + 2 )( x^2 + 4 ) 4) The middle term of the trinomial is always the OPPOSITE of the product of the two terms in the binomial - (x)(2) = -2x 5) ( x + 2 )( x^2 -2x + 4 )

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