Talk:Extraneous and missing solutions: Difference between revisions

Revision as of 15:45, 2 March 2008

Revision as of 05:00, 29 March 2008

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== Possible errors ==

I see a couple of things in this article that don't seem right. Firstly, with the example <math>\sqrt{x}=-1</math>, the article says x=1 is not a solution. That means <math>\surd</math> is being used to mean positive square root (as is common), but in that case the equation has no solutions by definition, so is a rather poor example. Secondly, at the end it says multiplication is surjective by not injective. It's quite clearly not surjective since it's image is just {0}. Am I missing something here, or should I just fix it? --[[User:Tango|Tango]]
([[User talk:Tango|talk]]) 23:24, 1 March 2008 (UTC)

:I've removed the last section because it is mostly incorrect, not easy to fix, and essentially [[WP:OR|OR]]. I wish the article had not been expanded to cover missing solutions, which makes everything a lot more complicated, and as far as I know is not a common term to describe errors that may arise in solving high-school algebra problems. &nbsp;--[[User talk:Lambiam|Lambiam]] 15:45, 2 March 2008 (UTC)

== Extraneous solutions in applied problems ==

There is another type of extraneous solution, that is not mentioned in the article. A solution to an equation arising from an applied problem may be considered extraneous if it is not physically meaningful. A negative length could be an example of this. See http://mathcentral.uregina.ca/QQ/database/QQ.09.02/paul2.html [[Special:Contributions/66.41.7.193|66.41.7.193]] ([[User talk:66.41.7.193|talk]]) 05:00, 29 March 2008 (UTC)