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【8 ÷ 2(2+2)=?】ネットで話題になった数式に数学者が答えた答えたとは? ★11

1 :みつを ★:2019/08/05(月) 04:12:21.45 ID:VytURMVm9.net
【8 ÷ 2(2+2)=?】ネットで話題になった数式に数学者が答えた答えたとは?

2019/08/03

https://www.nytimes.com/2019/08/02/science/math-equation-pedmas-bemdas-bedmas.html

The Math Equation That Tried to Stump the Internet

Sometimes BODMAS is just PEMDAS by another name. And no, the answer is not 100.

CreditCredit
By Steven Strogatz
Aug. 2, 2019

807
Mathematical Twitter is normally a quiet, well-ordered place, a refuge from the aggravations of the internet. But on July 28, someone who must have been a troll off-duty decided to upset the stillness, and did so with a surefire provocation.

It has to do with something that high school teachers call “the order of operations.” The latest blowup concerned this seemingly simple question:

https://twitter.com/pjmdoli/status/1155598050959745026?s=21

Many respondents were certain the answer was 16. Others heard Yanny, not Laurel, and insisted the right answer was 1. That’s when the trash talking began. “Some of y’all failed math and it shows,” said one. Another posted a photo showing that even two different electronic calculators disagreed. The normally reassuring world of math, where right and wrong exist, and logic must prevail, started to seem troublingly, perhaps tantalizingly, fluid.

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The question above has a clear and definite answer, provided we all agree to play by the same rules governing “the order of operations.” When, as in this case, we are faced with several mathematical operations to perform ― to evaluate expressions in parentheses, carry out multiplications or divisions, or do additions or subtractions ― the order in which we do them can make a huge difference.

When confronted with 8 ÷ 2(2+2), everyone on Twitter agreed that the 2+2 in parentheses should be evaluated first. That’s what our teachers told us: Deal with whatever is in parentheses first. Of course, 2+2 = 4. So the question boils down to 8÷2×4.

And there’s the rub. Now that we’re faced with a division and a multiplication, which one takes priority? If we carry out the division first, we get 4×4 = 16; if we carry out the multiplication first, we get 8÷8 = 1.

Which way is correct? The standard convention holds that multiplication and division have equal priority. To break the tie, we work from left to right. So the division goes first, followed by the multiplication. Thus, the right answer is 16.

More generally, the conventional order of operations is to evaluate expressions in parentheses first. Then you deal with any exponents. Next come multiplication and division, which, as I said, are considered to have equal priority, with ambiguities dispelled by working from left to right. Finally come addition and subtraction, which are also of equal priority, with ambiguities broken again by working from left to right.
(リンク先に続きあり)

https://static01.nyt.com/images/2019/08/02/science/02EQUATION1/merlin_158743359_ff291f8a-d473-4849-9d81-9762826b55f4-articleLarge.jpg?quality=75&auto=webp&disable=upscale

★1のたった時間
2019/08/03(土) 23:56:14.48

前スレ
【8 ÷ 2(2+2)=?】ネットで話題になった数式に数学者が答えた答えたとは? ★10
http://asahi.5ch.net/test/read.cgi/newsplus/1564928498/
https://twitter.com/5chan_nel (5ch newer account)
(deleted an unsolicited ad)

85 :名無しさん@1周年:2019/08/05(月) 06:02:40.57 ID:vOVQIXN80.net

>>65
実は2=2という文字式なんですよ

180 :名無しさん@1周年:2019/08/05(月) 07:02:20.34 ID:Qhkad4ps0.net

>>176
教えてるじゃん
>>162の疑問点あったら質問してくれたら答えるけど
この意味わかる?小学校3年生の算数だけど。
わからないよね、わかるはずがない。

162 :名無しさん@1周年:2019/08/05(月) 06:53:39.38 ID:Qhkad4ps0.net

>>23
その式って4×2×(2+2)なんだけど

8÷4で等分してそれにそれぞれ二個ずつのせたら
8÷4×2で、一人分のくだものの数が出るんだけど
それを4掛けないといけないんじゃないの?

ほんっとめちゃくちゃだよね
頭悪過ぎ。

ちなみにお皿が例えば5枚あって
1枚には赤い飴を二つ 1枚には黄色い飴を二つ 一枚には青い飴を〜とのせた時の式は
5×(2+2+2+2+2)じゃないから。

ひどい馬鹿だよね、めまいする。

657 : :2019/08/05(月) 09:43:06.10 ID:s32GAWND0.net

>>640
おまえのやり方は

ab(c+d)=abc+bd

16派は

ab(c+d)=abc+abd

198 :名無しさん@1周年:2019/08/05(月) 07:09:09.76 ID:A5Ybwcrb0.net

1以外の人は

2abc/abc が、2b^2c^2
に、なっちゃう人達だから頭が悪い

331 :名無しさん@1周年:2019/08/05(月) 08:02:11.03 ID:Qhkad4ps0.net

>>325
英語読めないの?
数学もできない英語もできない
何ができるの?

661 : :2019/08/05(月) 09:43:29.96 ID:s32GAWND0.net

>>653
>>640
おまえのやり方は

ab(c+d)=abc+bd

16派は

ab(c+d)=abc+abd

899 :名無しさん@1周年:2019/08/05(月) 10:50:03.12 ID:kNOOvwQ90.net

>>765÷の使い方が間違ってるからくくった
2(2+2)=2×(2+2)だが8÷2(2+2)=8÷2×(2+2)ではない

812 :名無しさん@1周年:2019/08/05(月) 10:28:31.75 ID:6+VFX+Eo0.net

>>791
だから16派の方が自然だって言ってるんだよ
あらゆる公的なツールは16としか計算しないのも証左

272 :名無しさん@1周年:2019/08/05(月) 07:42:35.76 ID:S5Yr95nx0.net

8÷(2(2+2))ではなく(8÷2)(2+2)にしか見えないという人が沢山居ことに驚いた
もはやアスペに近いだろ

2hcreate

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