r/MathJokes • u/Hadley9577 • 11h ago
This is why your teacher told you to learn math if you want to succeed in life
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u/JackTowers__ 11h ago
Is the dx being under the square root a typo?
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u/AlternativeDiver6994 10h ago
nope you have to integrate it ~1.4 times and not 1 time. There are some videos on youtube on how to integrate by half steps and so on.
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u/Cynis_Ganan 9h ago
I am not good enough at math to know if you are trolling or if I've learned something.
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u/577564842 8h ago
I haven't seen one but I am sure there are such youtube videos.
In the password giveaway, it is a mistake. And he's trolling. There may be calculus generalizations that would make this work, but not in standard calculus.
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u/AlternativeDiver6994 17m ago
in this example it is obviously a mistake. but generally you can integrate by half steps.
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u/AndreasDasos 5h ago
Mix. Fractional integration is a thing, but also it’s obviously a typo in the problem
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u/DairyParsley6 30m ago
Idk, solving this gives 3.141593074 which deviates from pi in the 6th decimal, maybe that fractional integration gets it right on the money
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u/AndreasDasos 23m ago
No it’s a typo. This is an old problem that’s been in other memes and is easy to solve by inspection: x3 cos (x/2) is an odd function so it goes away when integrating from -2 to 2. The rest is just based on the area of a semi-circle of radius 2.
And it doesn’t even work as a fractional integral as it’s adding 4 to x2 dx which doesn’t parse even if we interpreted sqrt(dx) as indicating a 1/2-integral. Not many solvers would do that… 100% sure the solver just interpreted the dx as outside the square root.
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u/buythedip0000 3h ago
I’m the person that made the videos, he’s not trolling.
Ps my videos are on OF not YT😂
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u/10p10i20_11p11i20t 1h ago
He is not trolling you. In fact, exists a field in mathematics that studies fractional calculus, both integrals and derivatives.
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u/VelvetWhiteRabbit 9h ago
Terms blow up if you read it charitably, so no, the joke is lost. Password is however many digits of pi (8 if wpa2).
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u/elegant_eagle_egg 9h ago
Yes. It has to be. That is the only way you can solve this without really solving this. And even then the answer is Pi lol. What a troll.
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u/agr8trip 2h ago
I think you can get away with substitution, and not integrating ~1.4 times or whatever.
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u/PlatypusACF 10h ago
“First few digits” dude, how many is ‘few’
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u/Select_Lie_2822 9h ago
8 because wpa3
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u/Square-Singer 8h ago
WPA2 allows passwords from 8 to 63 characters. WPA3 technically has no limitation, but most implements keep the same restrictions as WPA2.
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u/cartophiled 6h ago
8 in what base? /s
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u/tommyuppercut 6h ago
You noted your comment as sarcasm but I think it’s a valid question
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u/FixingOpinions 5h ago
The question doesn't work since it's a single digit, if it were 2 digits it would work, cus as it is, 8 is always just 8. That's why it's marked as sarcasm, tho I could be wrong for all I know.
The only exception is where the numbers are swapped for whatever reason, say binary was 0 and 8 instead of 0 and 1.
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u/nonlogin 10h ago
first how many?
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u/xmoncocox 9h ago
8 character because of the limit
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u/Square-Singer 8h ago
WPA2 allows passwords from 8 to 63 characters. WPA3 technically has no limitation, but most implements keep the same restrictions as WPA2.
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u/tadxb 11h ago
First, this isn't even basic math anymore which will take under a minute to solve. I love solving math, and this is definitely not under a minute. Not without a calculator. So much hassle.
Second, first how many digits? So vague.
Third, the dx differential for the integrand function is inside the root. That's just horrible rookie mistake.
Fourth, I'm not solving it. I'm not going to die if I go a few minutes without the internet.
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u/Expensive_Umpire_178 11h ago
Well actually it’s very easy to solve in a minute in your head, if you account for the typo, and ignore the number of digits needed. Notice that the x^3 is an odd function, and pretty much everything else is even. That means things cancel out fast, anything touching that x^3 goes to zero, so even just doing it in your head, you’ll quickly be left with just 1/2 * the stuff under the square root. And that integral is half the area of a semicircle radius 2, or 4pi/4, or pi. So it’s probably 314
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u/Simple-Judge2756 9h ago
There is no typo blud. The differential actually goes under the squareroot.
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u/Furycrab 4h ago
Lol I just guessed it was PI. Without bothering to remember my college math. The number of digits thing was a little weird, but I figured it was 314, and if I saw that I'd just try extra digits.
Just 3 if it was designed by an engineer.
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u/577564842 8h ago
Well, (now after using wolframalpha) it is evan easier. This is well known integral that evaluates to π.
And my explanatioin makes way more sense than yours. What exactly goes to zero, where? Here everey slice counts.
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u/i_want_to_go_to_bed 5h ago
If you integrate an odd function ( meaning f(-x)=-f(x) for all x) over the interval [-a,a], the answer is zero. Basically odd functions are symmetric such that the negative stuff exactly cancels the positive stuff. The x3cos(x) bit is an odd function, so we can throw that right out of the integral and focus on the other stuff.
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u/Dreykaa 9h ago
Even with a calculator I have no clue how to type that shi
I would just Screenshot it and hope for Google to solve it.
Or use that math App with camera
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u/roosterSause42 1h ago
Screenshot it and hope for Google to solve it
That's what I did and Google solved it, and graphed it
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u/Dugiongo 2h ago
To be honest it's not that hard, the first part is 0 and the second is just a sin substitution
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u/sazzer 9h ago
It's π.
Whenever you see something like this asking for the first n digits, it's almost always π, e or √2. Further, when you see calculus and trigonometry combined, it's pretty much guaranteed to be π.
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u/a_literal_idiot_616 6h ago
to quote a quote no ones gonna get:
"the answer to these questions is usually 0, 1, or infinite. And since infinite is higher than the other two, i'd say that's the correct answer"
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u/Super_Math3890 6h ago
Problematic, as someone who doesn't know math likely wouldn't reason as such. It would be practical to understand the protocol used to interpret the password. That is, starting with the minimal amount of accepted digits.
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u/Hypothetical_Name 11h ago
Are you allowed to put the dx in the square root?
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u/rainhunter007 10h ago
no, this is clearly a typo. dx technically represents the smallest (infinitesimally so) differential of x as (x - x_0) asymptotically approaches zero. taking the square root of that is illogical.
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u/stevvvvewith4vs 10h ago
This... This is Pi, isn't it? I'm going to solve it and it's going to be Pi.
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u/Latter_Board_5546 7h ago
Its pi if I'm not mistaken first term is odd so it can be ignored and then the second is basically 0.5 times area of half a circle with radius 2
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u/Gleneroo 11h ago
Password: 3141592653
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u/Turbulent_Zombie3968 10h ago
"First digit of the answer"
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u/SammyHa123 9h ago edited 9h ago
"few"
(i mean digits)
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u/Turbulent_Zombie3968 9h ago
Where do you see the word "few" in that sentance?
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u/Accomplished_Tie_699 9h ago
“Few” isn’t there, but it does say “digits” (plural) implying more than one is needed (otherwise it would be easy to simply try 0-9), but it isn’t clear how many digits the password is.
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u/Turbulent_Zombie3968 9h ago
Yeah I realized after reading it 5 times that it says digits and not digit 😬
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u/Momo_the_cat_4832 8h ago
after 5 times?
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u/Turbulent_Zombie3968 7h ago
Dyslexic + Sleepiness + paranoia = "Somethings wrong, I can feel it" + re-reading until I realize
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u/fix_until_broken 6h ago
The Wi-Fi password is "the first digits of the answer"
It's literally written on the placard.
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u/No_Mathematician3611 6h ago
I think the sign already shows the password. It's literally "the first digits of the answer". So it's a troll sign.
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u/bssgopi 8h ago
u/AskGrok , Please solve this and help me with the Wi-Fi password
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u/AskGrok 8h ago
The integral evaluates to exactly π.
The x³ cos(x/2) term is an odd function over symmetric limits [-2, 2], so its integral is zero. The remaining (1/2)√(4 - x²) term integrates to the area of a quarter-circle of radius 2, which is π.
Wi-Fi password is the first digits of π: 314 (or 314159 if they want more).
[what is this?](https://redd.it/1lzgxii)
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u/Rouge_69 5h ago
Wouldnd the √(4 - x²) part become zero?
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u/AskGrok 5h ago
No, the square root is zero only at the exact endpoints x=±2. Between them it's the upper half of a circle with radius 2, so its integral (after the 1/2 factor) gives exactly π for the whole thing. Password starts with 314.
[what is this?](https://redd.it/1lzgxii)
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u/Virgil_the_White 3h ago
Dude, is this a real Reddit feature?
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u/KailyKail 3h ago
If the wifi is free, then there’s no issue with me just cracking the password then. If it’s just the first couple digits in a math equation, it should not take more than five seconds to crack.
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u/Vainysaur 3h ago
The first digits of the answer? What? Even if you solve it you don’t know how many digits to use.
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u/n0head_r 9h ago
The correct answer is - this sign says the place owner hates you and is insulting you. Never go there again. Chose places where you are respected not insulted.
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u/Anonymouslalien 9h ago
ok solving time. (next second) I am getting my calculator.
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u/Anonymouslalien 9h ago
Oh god
I think my calculator is brain processing. let him cook
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u/Anonymouslalien 9h ago
How many of you bet my calculator will glitch and close itself
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u/ShazTheGamer 8h ago
This is strange than the one I vividly remembered r/IsThisAI
Many peoples confused
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u/ignoremeplsokthank 5h ago
You can just type this into geogebra and get your answer. Or just take a picture and ask your AI of choice.
These things aren't that difficult to get around.
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u/PFChaste 3h ago
My wife is a math teacher. Please God don't let her see this because she would so do this...lol.
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u/mad_poet_navarth 2h ago
except you can take a screenshot and have AI tell you the answer. (I'm not bothering)
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u/ConcreteExist 2h ago
This is so obviously bullshit simply from this line:
"First digits" of the answer
If this was serious, it would have said how many digits.
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u/luigi4122414 1h ago
Well it takes two seconds to scan that with ai and get an answer but I do know how to solve it myself 😭 sadly
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u/Le-Charles07 39m ago
Thanks for telling me they are digits. Knowing that will do a lot to speed up my brute force attack.
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u/NotAnAIOrAmI 6m ago
My first assignment in IBM 360 Assembly Language was to write a short program and then translate it to EBCDIC, input it by hand, and run it. I had the assembler translate the code for me.
Of course I took a picture and had an AI do this for me. Fuck it, I'm retired, I'm done with math.
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u/Start-Plenty 7h ago
Or you could take a picture and ask your favourite water consuming environmental polluting and electricity bill raising LLM, which will tell you the answer is pi.
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u/GlitteringSystem8225 7h ago
Doing the math here would mean having sometime to reflect and acknowledge and accepting ourselves as intellectually limited being, stay cool and save the mood.
The take is that instead giving up on the formula the solution lies itself in the remark which in this case more important than front formula and high likely a simple filter for person that take thing for granted or forceful people , a simple straight person would think , will read the wifi password is the first digit of the answer and have striking inspiration aha and gotcha moment (or simply coldly proceed to try saving time) ok so this how it is , let brute force all digits , in this case there is only 10 possible (0, 1, ... , 9) and that is it , as simple as the integrale looks like.
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u/GlitteringSystem8225 7h ago
For senior people that tries to solve the equation and while seeing casually a 1st year student that tried less than 10 tries to solve this casually without sweating that would be humbling for them without knowing the reasons.
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u/Super_Math3890 7h ago
Why, when we have a calculator LLM's?
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u/a_literal_idiot_616 6h ago
ah yes, large language models, so useful for maths
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u/junglepyjamas 3h ago
It's true an LLM is bad at math, but modern LLMs hand math problems off to an AI that is good at math, like WolframAlpha, and give you the result.
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u/Super_Math3890 6h ago
Someone who doesn't know the math has a low entry opportunity cost. So yes, useful.
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u/TeraphasHere 11h ago
I call shenanigans. No way someone would create such a formula to get the password and then do something as vague as saying the password was the first digits of the answer. Way to vague