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Path: ...!weretis.net!feeder9.news.weretis.net!news.quux.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> Newsgroups: sci.math Subject: =?UTF-8?B?UmU6IHjCsis0eCs1PTA=?= Date: Wed, 22 Jan 2025 14:57:28 -0800 Organization: A noiseless patient Spider Lines: 29 Message-ID: <vmrt4o$18f0k$1@dont-email.me> References: <4mVsl7f7IEYIck3oOw7iM3AOjN8@jntp> <vmrqo4$180ph$1@dont-email.me> <vmrs86$185g8$1@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Wed, 22 Jan 2025 23:57:29 +0100 (CET) Injection-Info: dont-email.me; posting-host="464af39ea2d015cab4edf118f2c36543"; logging-data="1326100"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+ZI6sPZp1F+k+20SsQ7aHVgRmQ0l8zteY=" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:nIWdcU5oJvholK9gkJWRZkygN18= Content-Language: en-US In-Reply-To: <vmrs86$185g8$1@dont-email.me> Bytes: 2009 On 1/22/2025 2:42 PM, Moebius wrote: > Am 22.01.2025 um 23:16 schrieb Chris M. Thomasson: >> On 1/22/2025 5:48 AM, Richard Hachel wrote: > >>> x² + 4x + 5 = 0 >>> >>> This equation has no root, and <bla> > > It has the two "roots" (solutions): > > x = -2 - i > x = -2 + i > > Hint: > > x² + 4x + 5 = (x + 2)² + 1. > > Hence x² + 4x + 5 = 0 is equivalent with (x + 2)² + 1 = 0 or (x + 2)² = > -1. So x + 2 has to be a (one or more) complex number(s) z such that z² > = -1. We know such numbers, they are i and -i (and there aren't more). > Hence we have x + 2 = i or x + 2 = -i resp. And hence x = -2 + i or x = > -2 - i resp. > >> The x^2 component has two roots. > > Doesn't make much sense. :-P Shit happens. When I see x^2 and think of complex numbers, I think of two roots. This can imply that there are two solutions.