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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Specialist Mathematics => Topic started by: NE2000 on December 11, 2008, 04:14:43 pm

Title: Expanding answers
Post by: NE2000 on December 11, 2008, 04:14:43 pm: I heard that in Year 12 you don't need to expand answers. Eg. if you get:
$(2x+5)(3x^{2}+4x+8)$

Then you can just leave it like that instead of expanding it and collecting like terms etc. Is that true?

EDIT: Changed simplify --> expanding to avoid ambiguity
Title: Re: Simplifying answers
Post by: dekoyl on December 11, 2008, 04:20:16 pm: I was told I had to do all the simplification in GMA which cost me in the exam. :(
Title: Re: Simplifying answers
Post by: Collin Li on December 11, 2008, 04:20:35 pm: Yeah. Expanded is not necessarily better than factorised (for polynomials).

Unless the question says otherwise (i.e.: "Express your answer in the form...") then there is no need to do extra work on it.

You should simplify things like $\frac{3}{12}$ and tend towards rationalising the denominator too.
Title: Re: Expanding answers
Post by: NE2000 on December 11, 2008, 04:36:57 pm: Thanks, the main reason I asked was because of things like the product rule where you can get some tedious expansions to do in the end and make a mistake in the middle even if you did everything else right...
Title: Re: Expanding answers
Post by: Collin Li on December 11, 2008, 04:46:53 pm: Ah... you should try to take out the common factor, and then the simplification usually becomes much easier.