Testwiki:Reference desk/Archives/Mathematics/2011 September 7

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September 7

infinity

Is infinity times infinity equals infinity valid math? — Preceding unsigned comment added by Organize this text file (talk • contribs) 18:58, 7 September 2011 (UTC)

Perhaps, but it really depends on the context, and how you are defining 'infinity'. It's a fairly meaningless statement without clarification. See e.g. indeterminate form, which covers many similar expressions at the level of basic calculus. Or, if you're up for it, check out the heavy stuff at cardinal number. SemanticMantis (talk) 19:43, 7 September 2011 (UTC)

I think that for any imaginable context, an infinite quantity times an infinite quantity is some infinite quantity, even if not the same one you started with. In the Extended real number line, yes, $(+\mathrm{\infty })\cdot (+\mathrm{\infty })=+\mathrm{\infty }$. -- Meni Rosenfeld (talk) 14:30, 8 September 2011 (UTC)