Not sure why the mark scheme does this (seemingly unnecessary) operation in the TMUA

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szchef
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The question:

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The question itself is not the issue, I completed it correctly up until this point in the mark scheme:
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How am I meant to know to do this? At first I thought I need to rationalise the denominator, but that simply lead me away from the right answer. Instead, they choose to divide the numerator and denominator by root(3) even though that doesn't divide rationally into -6 and produces a surd in the denominator anyway?
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user342
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What was your answer? I think it's just a case of 'simplifying' and comparing with the answers available then trying to get yours into one of those forms.
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szchef
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(Original post by user342)
What was your answer? I think it's just a case of 'simplifying' and comparing with the answers available then trying to get yours into one of those forms.
I got to 2root(3)x/root(3)x-6
Looking back at it now I suppose the only way to get to one of those answers was to get rid of the root(3), so I suppose you're right.
I still think it's a bit arbitrary though, to divide the numerator and the denominator by it for seemingly no reason.
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JustSomeGuy:/
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(Original post by szchef)
I got to 2root(3)x/root(3)x-6
Looking back at it now I suppose the only way to get to one of those answers was to get rid of the root(3), so I suppose you're right.
I still think it's a bit arbitrary though, to divide the numerator and the denominator by it for seemingly no reason.
It's only because that form looks cleaner. We mathematicians have a habit of wanting the nicest looking solution. Anyway it's good practice for noticing different forms of the same solution for the future.
Last edited by JustSomeGuy:/; 1 month ago
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