Complex numbers CONTRADICTION? (1 Viewer)

zando6

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hey guys
1. I proved that z^-1=conj z, converting into mod-arg form and by doing de moivres theorem so this must therefore be true
1/(2+3i)=2-3i

2. yet when i substituted z for an actual complex number eg. z=2+3i
and then did the realisation the answer is different
1/(2+3i) X (2-3i)/(2-3i)=(2-3i)/13

3. and i learned of a complex number rule where
z^-1=conj z/(mod z)^2
and this rule is consistent with what got ... which was (2-3i)/13

so now the question finally is why are there 2 answers that seem right?
 

Drongoski

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Pwnage101 made a good observation of a slip but made one himself. I'm not faulting him - just that it is so easy to make one, e.g. a typo.
 
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Pwnage101

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True. Thanks for that Drongoski. Lesson learned: don't be lazy and copy the LaTeX code from other people, and if you do make sure you have the right line.
 

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