J'ai été agressé par un soi-disant prof de maths sur Mastodon pour ne pas avoir utilisé une méthode que je n'ai jamais appris, n'étant pas Anglo-Saxon (BODMAS).

[silentexception@mastodon.social]

J'ai été agressé par un soi-disant prof de maths sur Mastodon pour ne pas avoir utilisé une méthode que je n'ai jamais appris, n'étant pas Anglo-Saxon (BODMAS). Heureusement, j'avais trouvé les notes d'un chercheur du CNRS. Et là voici carrément le résumé du problème. C'est toujours bon à connaître, mais ça n'excuse rien, et surtout pas les agressions verbales en commentaire. #maths #cyberharcèlement #cyberbullying

A vos méninges !

8 ÷ 2 (2+2)= ?Cette équation fait le buzz (en bon français) depuis quelques semaines. Voici l’explication de cette énigme mathématique, qui a fasciné jusqu’au très sérieux New York Times. Tout le...

(www.imt-nord-europe.org)

[fishface@ioc.exchange]

@silentexception Careful, you'll summon @SmartmanApps who will try to insist that he can "prove" that the only possible answer is 1. He can't, but he will certainly persist in increasingly unhinged bullshit to avoid admitting any error.

There is an additional nuance here which is that the multiplication in this expression - which is only implied, not denoted symbolically - is *typically* read as having a higher precedence than division, even though the *typical* practice is to otherwise perform multiplications and divisions from left to right.

This is almost *never* articulated explicitly in mathematics education as far as I can tell, so such expressions are rightfully seen as ambiguous.

The aforementioned user insists that 2(2 + 2) does not express multiplication (as would 2×(2+2)) but something else that he calls a "product". This is, of course, nonsense; a product is nothing more than the result of multiplication; 2(2 + 2) is just as much a product as 2×(2+2) is.

He then misreads certain explanations of how to simplify expressions using the distributive law as an instruction to apply the distributive law before all else, so, to him, this means expressing 2(2 + 2) as 4 + 4 *must* be done before anything else. He ignores the fact that textbooks show the evaluation of expressions in different orders, and that, when applied to an expression such as 2(a)³, it would have us rewrite it as (2a)³! (And then by ordinary laws of indices, this is (2a)¹⁺² = (2a)¹(2a)² = (2a)(2a)² = (2a2a)² = (2a)⁴ !!!)

Now you are forearmed in case this cyberbully happens upon you. I apologise for dumping this on you, and not in your native language as well, but hopefully you find it interesting/useful.