quote:
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Originally posted by Lugia
I don't know what's wrong with it... But I mean there HAS to be something wrong... Maybe I'll show my teacher tomolo.. hehe
oh I just remembered I've got this other one:
i = root -1
i^2 = root -1 * root -1
= root (-1 * -1)
= root 1
= 1
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Actually there IS a mistake here, the laws of surds, indices etc also hold for complex numbers, but there's a slight catch to it. Whenever you take the nth root of any complex number (i.e. any number over the complex field) you must expect n different answers. Therefore it is insufficient to say that the square root of 1 is simply one (in this context). You must give BOTH square roots of 1 (which are 1 or -1), just as if you were finding the 4th roots of 1(in which case the answers would be 1, -1, i, -i).
Therefore from,
i^2 = root 1
therefore
i^2 = +1 OR i^2 = -1
Because of the OR, only one of these equations is neccessary to be correct, so that is how it really should be done.