this post was submitted on 22 Nov 2024
55 points (98.2% liked)

math

804 readers
147 users here now

General community for all things mathematics on @lemmy.world

Submit link and text posts about anything at all related to mathematics.

Questions about mathematical topics are allowed, but NO HOMEWORK HELP. Communities for general math and homework help should be firmly delineated just as they were on reddit.

founded 1 year ago
MODERATORS
 
top 8 comments
sorted by: hot top controversial new old
[–] Stovetop@lemmy.world 83 points 11 hours ago (1 children)

As a not-math person, it's 0, right? Following the pattern, there would eventually be an (x-x) which would introduce a multiply by 0 into the problem and delete everything like a black hole from which no number escapes?

[–] Carnelian@lemmy.world 46 points 11 hours ago (2 children)

You are indeed a math person!

[–] ech@lemm.ee 11 points 8 hours ago (2 children)

Please correct me if I'm wrong, but x isn't specifically part of the sequence a-z, right? And a-z isn't explicitly a consecutive sequence. Both are implied, but they're all just placeholders for individual numbers, not necessarily in relation to each other.

If that is the intention, it's poorly done. (1-x)(2-x)(3-x)...(∞-x) is much clearer and understandable.

[–] Carnelian@lemmy.world 8 points 8 hours ago

I think it’s correct as is. The “…” is used when enough information is present to complete the series.

For example, if the series really is anything other than the alphabet as it is commonly understood, (thus excluding “x”,) then that would need to be made clear by the person communicating the series.

For example, we can say with confidence that your example, “1, 2, 3…∞” is indeed the set of natural numbers, including “24” if we were to write them all out.

they're all just placeholders for individual numbers

Just normal variables, although used in a kinda “gotcha” way by obfuscating the “number minus itself” trick. There’s a very common teacher’s trick that relies on the same principle. You balance a certain equation and “prove” on the blackboard that 0=1. It’s incumbent on the students, then, to figure out that halfway through your shenanigans, you divided the right half of the equation by “x-x”. This is dividing by zero, which is impossible, and thus explains your farce.

[–] Peruvian_Skies@sh.itjust.works 2 points 8 hours ago (1 children)

Correct. Let a-z be the first 26 prime numbers and x be an unknown real number, for example. It cannot be categorically stated in this case that it simplifies to zero.

[–] Carnelian@lemmy.world 6 points 8 hours ago (1 children)

Not correct. The variable “x” cannot represent both the 24th prime number as well as an unknown real number. If you wanted to represent your proposition it would need to be written differently than in the meme

[–] Peruvian_Skies@sh.itjust.works 1 points 12 minutes ago

But the problem with the meme is orecisely the ambiguity of whether or not x belongs to the set {a, b, c,...,z} due to x's universal use as "the" variable.