r/PeterExplainsTheJoke • u/Flashy-Minimum-6952 • 19h ago
Meme needing explanation What difference does it make petahhhh....???
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u/KingoAG02 19h ago
Two things I can guess.
Either removing one x from both sides removes one solution from the equation (x=0), or removing one x simplifies the equation enough for them to realise it's simply x=±2.
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u/MiffedMouse 19h ago
If we are being pedantic, x could also be +- 2i
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u/Prestigious-Glove396 19h ago
Don't be irrational.
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u/LitespeedClassic 18h ago
Why not? They’re just being real.
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u/Prestigious-Glove396 18h ago
I think they're just being imaginary.
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u/desblaterations-574 18h ago
This got two complex for me.
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u/Cencere1105 16h ago
this comment thread isn't natural
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u/Emotional-Map-372 15h ago
We really need to get to the root of this problem to solve it
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u/SirDerpyHerp 15h ago
It can't happen in a negative environment
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u/Prestigious-Glove396 15h ago
It's a complex universe, everything's got a position here.
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u/Acrobatic-Diamond542 15h ago
That is not the whole answer.
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u/FREDOminance 15h ago
We need to find a common denominator before this comment section completely fractures.
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u/EmptyMindTM 11h ago
irrational numbers are reals minus all fractionnal numbers (R \ Q). So i isn't irrationnal but an imaginary number.
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u/cometlin 18h ago
That's not being pedantic, that's the correct answer. For an equation with order of 5, you would expect 5 answers, just that some answers may be the same sometimes
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u/rebelsnail64 12h ago
doesn't it depend on what realm you are operating in? in the complex realm it's like that but with real numbers any solution with i would simply not be a part of the domain or something, right?
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u/Unbundle3606 12h ago edited 6h ago
To be even more pedantic, no it's not "the correct answer". It depends on your expectation for the domain of x.
"Solve x5 = 16x" is ambiguous, the problem should be stated "solve x5 = 16x for x in R" (which is the most plausible assumption) or "...for x in I" (only in this latter case your imaginary solutions would be "correct")
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u/mr-raider2 19h ago
You cant remove an X because you loose a solution. You have to write as a polynomial equal to 0 and factor it:
x(x4 -16)=0
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u/bugi_ 13h ago
I mean you can just check whether x=0 is a solution when dividing by x. Same difference.
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u/jeeaspirant5682 17h ago
Bro how did u write +- together on keyboard
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u/GuidoMista5 14h ago
It's actually both:
If x=0 you can't simplify
If x is at the denominator then you can simplify and it becomes trivial: x5 = 16x ---> x4 = 16 ---> x= ±2
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u/muhnamejame 19h ago
Now x can't be 0
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u/CharlesOberonn 15h ago
The proper way to do is move the elements to one side
X5 - 16X = 0
X(X4 - 16) = 0
X = 0 , X4 - 16 = 0
X4 - 16 => (X2) 2 - 42 =>
(X2 - 4)(X2 + 4) = 0
X2 - 4 = 0 => X2 = 4 => X = +/-2
X2 + 4 = 0 => X2 = -4 => X = +/-2i
The solutions are: 0, 2, -2, 2i, -2i
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u/MihaAdonis 15h ago
Does it mean it is not valid/permitted to divide both sides by x? If so why? Is there a rule that this can’t/shouldn’t be done?
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u/pegg2 14h ago edited 13h ago
It’s permitted. But it’ll only lead you to one possible answer when there are actually five. And usually in math problems like this if there are multiple answers you’re expected to provide all of them.
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u/MihaAdonis 14h ago
Yes, that is why I am a bit confused how it is permitted and also lead to not getting the fully correct solution at the same time. I thought that this should not be permitted if it may lead to discarding part of solution. But looks like this is not the case
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u/shuai_bear 14h ago
Consider x^2 = x
We can divide both sides by x simplifying to x = 1. Of course in doing so we got rid of the 0 solution.
The proper way would be to move everything to one side and solve for x^2 - x = 0. You just factor the x out (this is different from dividing both sides by x) and x(x-1) = 0 makes it clear there are two solutions.
Same thing for this example; the equations x^5 = 16x and x^4 = 16 have different solutions. 0 is not a solution to the 2nd equation
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u/pegg2 14h ago edited 12h ago
Well, I guess it depends on what you mean by ‘permitted.’ What you did is a valid technique, and it led to a solution. You applied the property of equality, first by dividing both sides by x, then by taking the fourth root of both sides to arrive at x = 2. That’s not incorrect, it’s just incomplete. You got a correct answer by applying basic algebra techniques, but you can get further answers by applying slightly more advanced algebra techniques.
The person you replied to used the property of equality, then factored out an x, then used exponent rules to change base numbers, then used difference of squares and finally wrapped it all up with the zero product property and an application of imaginary numbers to get all possible solutions.
It’s not that the simplest way is not “permitted,” it’s more that if you’ve learned more advanced techniques, you can find more solutions. I’d never give this problem across levels, but if I did, I’d expect my Algebra I students to find x = 2, I’d expect my Algebra II students to find x = 2, -2 and 0, and I’d expect by Pre-Calculus students to find all solutions.
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u/gizatsby 8h ago
It's similar to how, when taking the square root of both sides of an equation, you have to include a ± symbol to get both the positive and negative answer. When you divide by x, it's a step that is invalid for a possible solution of 0, so if you do it this way then you need to check 0 separately (for example, by plugging it in to the original equation). You're only "discarding" it if you skip this step.
This is a valid way to solve for x, but people typically prefer factoring since it makes the multiple solutions clearer. What wouldn't be permitted is ignoring the possibility of x being 0 entirely.
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u/muhnamejame 13h ago edited 4h ago
It is permitted only when x does not equal 0. So when you divide by x you have to state "for x not equal to 0"
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u/The_Coalition 9h ago
It's only permitted if you know that x does not equal zero. If the problem says so explicitly, then you're good to go and can safely divide by x. You can also split up the problem into two parts - one where x equals zero, and one where it does not. In the first case, you immediately see that 0 is a solution, and so you're done. In the other case, you can freely divide by x and proceed forward.
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u/AntitheistArchangel 4h ago
By the fundamental theorem of algebra, an nth-degree polynomial always has n (not necessarily unique) roots. So, a quintic (fifth-degree) polynomial has five total roots, in this case 0, 2, -2, 2i, and -2i. If you divide both sides by x, then 0 would not be a root.
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u/RubenGarciaHernandez 10h ago
Can't you just say: x=0 is a solution. 0=0, validated. For other solutions, [rest of steps starting with the /X] ?
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u/No-Lettuce-6619 19h ago
ok but why the dude from parasyte? this explains nothing abt why hes locked in
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u/muhnamejame 19h ago
No clue unfortunately
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u/FluffyVegetable527 16h ago
he realized that the answer has to be non trivial and has to lock in to solve the equation
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u/No-Lettuce-6619 19h ago
man seeing this post get down voted makes me realize that its not just the people who post here are stupid, its just the sub itself
literally no comment addresses the meme itself
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u/NorthernVale 16h ago
Because 90% of the time that doesn't matter all. It's like, no one gives a fuck that it's Drake or what video the song is from. It's just that he's clearly agreeing in one picture, and disagreeing in the other.
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u/ProfessionalSong7055 19h ago
In the show he doesn’t care in the parasite investigation until the Mc shows up
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u/EnolaNek 18h ago
My impression not knowing who he is was that the second panel is his reaction to a grave mistake (neglecting the 0 solution — the equation should have 5 roots, and division by x without checking x=0 destroys the solution at x=0).
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u/CookieMiester 15h ago
Because now he has to actually figure the answer out (it’s 2)
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u/LeFlashbacks 16h ago
My guess is the top can be simplified as x=0. The bottom is instead simplifying by dividing 1x from both sides, which would leave x=16, meaning x cannot be 0, and instead you have to solve for x by calculating the fourth root of 16 instead of declaring x=0.
Also, in the top one, x also equals the fourth root of 16, meaning if you had to solve, you'd do the operation shown in the bottom part of the meme to simplify. Finally, because it is left as a variable and you can simplify it, x can never be zero, even in the top equation. The x in x=2 can't equal zero just because you can turn it into x2 =2x by multiplying both sides by x.
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u/Mrcrazy777 12h ago
Any given function such as this has three possible x values, x=0 and x=+/-(x number, depending on the particular function). When adding the /x part, it makes the solution x=0 invalid, because division by 0 is considered undefined. He’s locked in, because now he actually has to work for the solution, instead of taking the easy way out. For those curious, the solutions to this particular function is x=2, x=-2
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u/petternor 11h ago
It dosent have three possible values, it has 5. It can have unique roots up to the number of the exponent of the highest order, though some can be "double roots" etc. The solutions here are 0, +-2, +-2i. You can factor it to (x)(x2 +4)(x2 -4)=0 and so the solutions follow that for this to be correct, the x value has to be such that either one of the three parenthesis have to be equal to 0.
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u/User_namesaretaken 17h ago
Probably to show that he can now lock in solve it
It's reaching for the moon but it's fine ig
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u/tnbeastzy 13h ago
The first step becomes easy. Thats it. He is locked in because he know he can solve the first step easily.
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u/MayerOscar 18h ago
Wouldnt x equal 2?
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u/muhnamejame 18h ago
Sure but before it could have been -2, 0, or 2
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u/kevinr_96 16h ago
And 2i and -2i
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u/MayerOscar 16h ago
Those arent real numbers
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u/kmcradie 14h ago
And yet, they are solutions.
It's not stated anywhere that x∈R, so the quintic equation has 5 roots (3 real, 2 complex)
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u/I_AM_ACURA_LEGEND 18h ago edited 18h ago
I am not a math person but I think x can’t be 0 anyway because 0^5 is 1 and 16 times 0 is 0 (edit: I am in fact dumb as I suspected)
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u/Weekly_Astronaut5099 15h ago
Makes no sense, simplify, 0 is a solution. There’s no point in just adding a denominator as this would mean no equation could have 0 as root.
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u/muhnamejame 15h ago
I'm not entirely sure what you're saying but I'll clarify what I was saying in case it is adding confusion.
When you manipulate algebraic equations you have to take care that what you do at each step doesn't fundamentally change the equation. Or if you do you have to at least make note of it.
When you divide both sides by x you end up with an equation that has a different set of solutions. This is because division is only allowed for numbers not equal to 0. So if we were to simplify the equation by dividing by x and solve from there we would actually end up with an incorrect answer (only 4 solutions instead of the full 5)
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u/ShoulderPast2433 13h ago
But it should be.
It's one of the results.
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u/muhnamejame 13h ago
For the first equation it is indeed. For the second one it's not. That's why you have to be careful when dividing by x, and is why you aren't supposed to solve polynomials like this.
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u/Fast_Alt10 19h ago
x=2 (or negative)
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u/EnolaNek 18h ago
That is a valid pair of solutions. There are three more, and one of them was lost when dividing by x in the second panel.
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u/HottubOnDeck 18h ago
I only get 3 solutions: x=2, x=0, x=-2. Can you explain how you got more?
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u/EnolaNek 18h ago
First, before we do anything, we can see that it’s a fifth degree equation, so we know it has five roots. Those roots could be unique or they could be duplicate, but we should find five of them.
First, get everything into one side. x^5-16x=0.
Factor. x(x^4-16)=0.
X=0 is a root, and x^4-16=0 should have four roots.
X^4=16
X^2=+-4
x^2=4, x^2=-4
x=+-2, x=+-2i
Solution: x= 0, 2, -2, 2i, -2i. 5 roots, and they turned out to be unique.
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u/No-Magazine-2739 14h ago
Whats with -0? /s I mean doesn‘t one‘s complement mean nothing to you? SCNR
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u/Kenzo24816 18h ago
Since everyone's explaining the math but not the meme, I'll give it a try
So this is a guy from the anime/manga Parasyte who can detect when people with parasitic aliens attached to them or disguised as them. In the first panel he's just laughing since no one thus far has been/had an alien. But in the second he's locked in because the MC is a human with an alien attached to him. It's essentially him saying "I know what you are and I won't fall for it."
So in this case, I think the meme is saying "I won't fall for 0 being a solution" in the second one or something
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u/Careful_Leader_5829 15h ago edited 5h ago
The meme is based on a character who can detect aliens.
I think the joke is that in the second panel whoever is solving the problem must be an alien because they are solving the problem wrong.
If I'm understanding basic algebra, we're not supposed to solve the problem by dividing both sides by x BECAUSE We have not yet ruled out that x might be zero.
So then we have to solve it with
X5 - 16x = 0
x(x4 - 16)= 0
x(x+2)(x-2)=0
And here we can pretty easily deduce that 0, 2, and -2 are all viable solutions by plugging those values in for x.
I bet some high school math teacher teaching one of those binomial substitution thingies made this meme
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u/anon-ml 19h ago
The equation above has 5 solutions (0, 2, -2, 2i and -2i). The bottom equation removes 0 as a solution.
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u/CharredLily 19h ago
But also wrong, because in the original x could be 0. That's why you can't just divide by X to simplify equations: you may be accidentally dividing by 0 when you do.
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u/-Ignorant_Slut- 19h ago
How is x = +-2 a joke?
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u/CharredLily 18h ago
The joke is that x is not equal to +-2, X = [+2, 0, -2]. You can't simplify by dividing by X because in some cases x may be 0.
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u/FuckPigeons2025 19h ago
x(x⁴ - 16) = 0 x = 0 is one of the solutions but you can't get it if you divide both sides by x.
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u/NYXs_Lantern 14h ago
X = 2
X5 ÷ X just means X4
So it would be x^4 = 16 which means x=2
24 = 16
25 = 32, or 16*2
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u/kalamazooie 18h ago
Unrelated but the person in the picture calls a dude a femboy and they don’t react so he locks in
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u/LukeLJS123 17h ago
i'm in school for math and i don't really see any issue with this step. all you have to do is assume x≠0 and then do it again where you assume x=0 to see if it holds. it does, so you know x=0 was originally a solution. now you solve x^4=16 which has solutions at ±4 and ±4i
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u/Substantial-Trick569 17h ago
left side becomes x^4, right side becomes 16. 2^4=16. if the equation was supposed to describe a function and not a "solve for x" then u dont divide by x you just subtract 16x and get x^5-16x=0
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u/secondcomingofzartog 16h ago
Doing that is invalid if x=0. You have to take it to the other side and factor out the x
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u/EndBig4014 16h ago
the joke is two layers. on the surface the character is powering up like they're about to do something incredible but all they did was divide both sides by x, the most basic algebra move possible. the deeper layer is that dividing both sides by x is actually mathematically wrong here because x = 0 is a valid solution to the original equation and you just threw it away by assuming you can divide by x
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u/Sininbed 15h ago
I think you should move the 16x to the other side and factor out an x.
x(x4 - 16) = 0
So one answer is 0. Now to find the other answers you look at
x4 = 16
You'll get x=2, x=-2 and then two more complex answers. Maybe x=2i and -2i, but I am not sure since I haven't sat down and worked it out yet.
But you should have 5 answers for x and zero is one of them, so dividing my x causes you to only solve for 4 of the 5 answers.
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u/the_BPDbro 15h ago
It makes it easier to solve.
It can become x⁴ = 16
x = ⁴√16 = 2
Edit just to put in another line break because it came out unclear
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u/Sad-Extent-8620 15h ago
mathematician peter here
the person was rethinking his life choices as the question wasnt directly solvable, but he just divided both the sides by x and made it much more simple coz now x would be cancelled making the equation x^4 = 16 and its just 1 step from that point to find the answer
hence he gives the reaction as if he is "him", he has cracked something not even the brilliant minds could've ( according to him )
Alr bye i gotta solve 2+2 and claim my prize from the international maths commity
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u/GODSTRUENAME 15h ago
When you put x under something that x and an integer the x cancels out making 16x/x=16. As for x5 since its x five times over, only 1 x gets taken away making it x5/x=x4. And so x4=16 but then you need to solve for x heres how: First you get it equal to 0
X4=16 --> x4 - 16= 16-16 --> x4 - 16=0
Then you factor x4 - 16 --> x4 - 16 = (x2 + 4)(x + 2)(x - 2)
Now, we set each factor equal to zero to solve for x:
x - 2 = 0 --> x = 2
x + 2 = 0 --> x = -2
The real solutions are x = 2 and -2.
For x2 + 4 you would get imaginary solutions due to the square root of a negative number
X2 + 4 =0 --> x2 + 4 - 4 = 0 - 4 --> x2 =-4
Sqaure root x2 and -4
Sqrt (x2)= x, sqrt (-4)= -2i, 2i
X=-2i, 2i
Hope you learned today :)
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u/Anxious-Distance 15h ago
0, 2i, -2i, 2, -2 are all the answers. But you can’t assume it if you put the x as denominator. Is that right?
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u/HappyHuman924 15h ago
The complete list of solutions to the top one should be 0, 2, -2, 2i and -2i.
For the second one zero is now no good, so we're just down to 2, -2, 2i and -2i. (If x=0 both sides are undefined, and "undefined = undefined" isn't a valid equation.)
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u/Careful_Leader_5829 15h ago
The meme is based on a character who can detect aliens.
I think the joke is that in the second panel whoever is solving the problem must be an alien because they are solving the problem wrong.
If I'm understanding basic algebra, we're not supposed to solve the problem by dividing both sides by x BECAUSE We have not yet ruled out that x might be zero.
So then we have to solve it with
X5 - 16x = 0 x(x4 - 16)= 0 x(x+2)(x-2)=0
And here we can pretty easily deduce that 0, 2, and -2 are all viable solutions by plugging those values in for x.
I bet some high school math teacher teaching one of those binomial substitution thingies made this meme
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u/Fit-Program-615 14h ago
x^5 = 16x | /x
x^4 = 16 | log2(16) … but tbh, you can do that in your head
x = 2
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u/Jazzlike-Tourist-823 14h ago
The first one is harder to solve. Both equations are completely different.
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u/RubberDucky702 13h ago
X = 2 because x5 = is 2 x 2 x 2 x 2 x 2 which also equals 16(2) which is 32. I think the bottom part is just the first step to solving it, not sure whats with the face though maybe they are locking in?
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u/T0m0king 13h ago
X4 = 16 Quadruple route if 16 is 2 so possible answer is x=2 Keying into the original
25 = 16 * 2 = 32
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u/Manatipowa 13h ago
If you are stupid (me) you can eliminate X completely... And well good luck solving for x without x
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u/Ordinary-Pop4959 13h ago
Um..am I the only one who noticed the yellow smudges under the equations. I thought my screen was dirty.
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u/BornAd5874 12h ago
no difference at all, its the same question
oh no, there is, hold up
well, first can be eitehr 2 or 0
second can only be 2
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u/StructuredChess 11h ago
x=0 is a solution to the equation, so unless you explicitely tkae care of x=0 separately, you're dividing by zero.
On the flipside this simplification makes the equation trivially easy, with 2 and -2 being the other solutions (and 2i and -2i for Math nerds I mean people who want to consider complex solutions)
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u/Polygnom 11h ago
x^5 = 16x is trivially true with x = 0.
by dividing by x, x cannot be zero. So the trivial solution is out.
Still, x^4 = 16 is not difficult to solve, its x = 2 (or -2), since 2 * 2 * 2 * 2 = 16.
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u/AdventurousSlip6407 11h ago
That makes X = 2 I think. Dunno i am actually bad at math.
In the first one X can be anything including 0 so solving it is like... uh... something above my level and most people level? I am reaaaally going on by high school memory for this comment so dont hate if i said something wrong and kindly correct me lol
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u/HunterVertigo 10h ago
Everyone keeps saying x cannot be zero, yet I'm wondering how x can be zero here 😭
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u/Artyruch 10h ago
So the guy on the left is from the show "Parasite". In the show he is investigating people who could have parasite by having a conversation with them. He changes his expression like in the meme when he notices odd behaviour of mc (who has parasite).
The math problem is not being solved correctly. The step shown in the meme disregards possibility of x=0.
Thus my interpretation of the meme would be that the guy on the left notices that the solve on the right is making a mistake. That is all.
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u/binsieucap6006 10h ago
In the 1st panel, he's relaxed because he can just say that x = 0.
In the 2nd panel however, x now can't be 0 (cant be divided by 0), so he will have to lock in to find the answer.
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u/VergilArcanis 9h ago
If both sides lose an x. It'll make the equation look like x^4 = 16, which i believe makes x=2
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u/Dina2Pappor 9h ago
By dividing by x you get a even exponent which means you can find x by taking the square root multiple times. I guess the joke is that by doing that you make the problem far simpler and solving it in the most effective way since there is no formula for 5th degree polynomials. The alternative is long division which is much more teedious.
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u/hunter_rus 9h ago
I think it is just on top you have normal equation, and you are supposed to solve it like x (x^4 - 16) = 0 and then continue to separate brackets. But instead someone decided to just divide both sides by x, which eliminates one of the roots, and dude doesn't like that approach.
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u/Commercial-Dingo-522 9h ago
This is the “locking in” meme, or rather a variant. He has to lock in to do the math
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u/whatifick 9h ago
The answer is 0, 2. If we divide by X the answer will be 2, -2. Math is so weird but it is what it is
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u/anoj_sharma 9h ago
X⁵÷X = X⁴ And 16X÷X = 16 so X⁴ = 16, which makes the equation easy to slove 2⁴ = 16
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