Sujet : Re: Division of two complex numbers
De : invalid (at) *nospam* example.invalid (Moebius)
Groupes : sci.mathDate : 21. Jan 2025, 11:37:20
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Organisation : A noiseless patient Spider
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Am 21.01.2025 um 11:27 schrieb Moebius:
Außerdem macht "(a, b)^2 = a^2 + 2ab + b^2" nach wie vor keinen Sinn.
Let's write the complex number (a, b) in the usual form a + ib. Then
(a + ib)^2 = a^2 + i2ab + (ib)^2
by the binomial formula (!). Hence
(a + ib)^2 = a^2 + i2ab + (-1)b^2 = (a^2 - b^2) + i2ab .
And hence
(a, b)^2 = (a^2 - b^2) + i2ab (!)
or rather
(a, b)^2 = (a^2 - b^2, 2ab)
would be correct.
( Knapp daneben ist auch vorbei. :-P )
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