TikTok is a bad math goldmine! Solving x+2=x-2. Reddit r/sciencememes
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- เผยแพร่เมื่อ 25 ส.ค. 2024
- Learn how to correctly solve the equation x+2=x-2. Subscribe to @bprpmathbasics for more algebra tutorials.
Original post on Reddit: / qjsr7xycd4
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#math #algebra #mathbasics
1 divided by 0 (a 3rd grade teacher & principal both got it wrong)
th-cam.com/video/WI_qPBQhJSM/w-d-xo.html
You wasted your time with this video.
If you apply limits and assume x is going to negative or positive infinity you get an answer.
*Reddit* isn't any better.
@@ToguMrewuku Hi #bot
@@adam.maqavoy at least reddit has downvotes and a place for math, so people know if they're wrong
Let's be honest, you can already see just by looking at the question that this will have no solution...
Yes, I can.
This stupid comment has more likes than the comment below this, which has actual valuable information unlike this junk
(X+4) does not equal x
Who came up with it was for sure just writing down random numbers, the statement "a number plus two is equal itself minus two" is a paradox
@@devookoWell not exactly that because it is still working out something, you can just read it and say no soln exists, because the statement essentially says that find x such that increasing x by 2 is the same as decreasing x by 2, which is not possible. So no solution.
"x+2=x-2"
"No it doesn't"
Nuh uh
"Time of day" + 12 hours = "Time of day" - 12 hours
@@khaitomretro you missed a (mod 24) at the end
@@kebien6020 "x+2 = x-2... in ℤ₄; I'm fine!"
@@khaitomretro no. That cannot be used to solve this problem.
Guy had the mental prowess to apply difference between two squares, but not enough to do the first step right💀💀
That's how you can tell that this is almost certainly someone yanking our chain. Most of the algebra is just to distract attention from the blatantly ridiculous first step.
Bros probably solve the 1st line, then ask chatgpt to solve the rest 💀
What he is showing first is the solution from the TikTok video. Then he proceeds to show how it is wrong.
@@cybore213 OC wasn't talking about bprp
@pegasoltaeclair0611 Thanks. Sometimes it's hard to figure out who the comment refers to. But I should have figured out that the OP was referring to the guy who posted the TikTok answer.
This is not math this is meth
😂
I was looking for comment like this. I got micro aneurysm just by looking at it: x+2=x-2 ==> (x+2)(x-2)=0, followed by second step.
Yea maybe in some imaginary cosmos where law of mathematics and physics don't exist created by TikTok's influencers.
Meth is herd
@@Mike_B-137
TikTok managed to combine additive and multiplicative rules together.
Because if you divided one side to the other, the other side would be one. If you multiplied, it would be (x-2)(x+2) but the other side would be (x+2)^2. Not 0.
Also, if you subtract the one side, you would get zero, but, the other side would = 4. Which, that is one way to find no solutions just like subtracting just the x on both sides. The problem is they multipled on the left side, but, subtracted everything on the right. And broke Algebra rules.
So, they applied multiplication to the left side and then assumed the right side would cancel to 0. Remembering some of Algebra but forgot you have to subtract.
And then after that incredibly wrong step, it just gets stranger and more wrong. Lol.
Gosh. I think the comment may possibly be a troll. Lol.
To mess with TikTok, but, not 100%. Could be someone overconfident in their Math abilities.
Either way, they seem to have just kept working until they found a solution somehow. And each step seems reasonable to someone untrained in Math, but, to someone who is trained in Math, it is obviously wrong and insane each step of the way to a misshapen "solution".
I saw some tiktok coders through other platforms and it was down bad, but this is too much, how come as a society we need to explain x+a = x-a if a /= 0 is wrong. System has failed.
My eyes are bleeding from the proposed solution
I mean they literally could’ve just checked it, there is no way 2+2 = 2-2 (if you use sqrt4 which idk why they didn’t even simplify it down to just 2 but I digress)
There's nothing wrong with the way they've written it because √ is always positive.
I think the thing is that -2+2=2-2.
@@error_6o6but you're saying x=-2=2
Quadratics can have multiple solutions, x=2, x=-2 indicates that x could be either, and not that it is both
-Remembers the negative square root
-Forgets division exists
The fact that he had zero on the right, not 1 implies he was mixing up subtracting with multiplication, not division.
No, he simply copied what tiktok gave as the answer and then explained why it is complete bullcrap.
The tiktok was a joke, literally.
@@Kyrelel talking about the commenter, not the guy explaining
@@KyrelelWe say “Once TikTok was launched, parents’ nurture f**ked up”
(It’s Chinese, I try to translate it, but it still mean TikTok mess up everything)
That proposed solution is got to be a ragebait ,
How did you do that?
@@blacklight683 there is no sol.
I hate how the first step is (x+2)(x-2)=0, which immediately implies x=±2, and then the TikTokker goes on to undo that and expand the quadratic out so that they can solve it by taking square roots instead. That almost bothers me more than the fact that the first step is completely bogus.
The average tiktokers knowledge of math:
it’s probably a 12 year old who was just really eager to use the new identity he learnt
@LumiaFenrir-nn2pz and you’d be surprised by the number of Asian fetuses that know how to solve quadratic equations in microseconds
Not simplifying into 2 is probably intentional so that people won't just mentally check their solution and find out how garbage it is.
Bro got a degree in psychology but failed math 💀
Ахуеть, я только что узнал, что у слова "фигня" есть английский аналог.
@@user-qi2jg2zb5lне пиши сюда больше никогда
Lol yea most people just nope out seeing square roots even though this one is quite simple. But that means they won't catch how the answer doesn't even work if you plug them in which is checking your work 101
I have a solution, change = to ≠ 😅
Surely,
The equation
x + 2 = x - 2
should be replaced with
x + 2 ≠ x - 2
another solution is changing = to >
x+2=x-2 (false)
x+2>x-2 (true)
Another solution, the equation is in Z/2Z
I love this comment. 😂
@@wqrwtrue dat.
Computer Scientist: "x = x+1"
Mathematician: "Nuh uh"
Computer science square root of -1... because computers don't work without "I"
It's really unnecessary to do anything past subtracting x on both sides, you got 2 = -2, a likewise always false statement like 0 = -4. What I wanna know is how somebody thought dividing (correction: multiplying) both sides by x - 2 would give 0 on the right side. 🤣🤣🤦🏾♂🤦🏾♂
Even worse, this was obviously multiplying both sides with (x-2).
That was not dividing both sides. That was multiplying the left side by (x-2) while SUBTRACTING (x-2) from the right side to give that zero.
What was done as the first step is this : (x+2) = (x-2) → (x+2)*(x-2) = (x-2) - (x-2) → (x+2)(x-2) = 0
@@KualinarNono, it was just dividing both sides by 1/(x-2). I don’t know what composition rules they’re working under where that equals 0 on the right hand side, but technically it was dividing both sides by 1/… just as much as it was multiplying by (x-2)
@@Tristanlj-555 Dividing can never reduce a value to zero. ONLY a subtraction can do that.
Then, a division by (x-2) would have made the left side into THIS : (x+2)/(x-2) NOT (x+2)*(x-2)
@@Kualinar I know that. I just finished my last exam, complex analysis for my first year of mathematics at Uni. I alluded to that jokingly by mentioning composition rules.
The question goes like:
I love Math = I hate Math
It's a love-hate relationship
Hes getting stronger.
He can manipulate the board by sinply tapping it with the back of his marker.
We must stop him before its too late
😂
One day he shall no longer have a need for markers, his mind is enough
The real answer is not in finding x.
The real answer is that this addition is defined over ring of remainders of division by 4.
In which 2 = -2 since 2+2 = 0.
Therefore, the equation is true for any x.
We are threading in the realms of abstract algebra, where everything is possible.
Lmao! 😂😅
He edited it out
This is why you should always plug your solution into the original equation to make sure it's correct.
You'll run into a problem here, the solution they got is x = 2 or -2. If you plug in -2 on the left and 2 on the right it technically works. Obviously you're supposed to do the same number for both x values but we're past the point of them doing the right thing.
@@jacobisbell9388 Yeah to be fair that makes sense.
@@jacobisbell9388yea but even just looking at the equation, how would x plus n be equal to x minus n.
no calculations needed.
@@Tealen
Unless n is 0, which it is not.
@@Pingwn yes, in this case its 2. I should have mentioned it
I love the tap erase. Super tech white board ;)
Thanks!!
I got it from Amazon haha
@@adityagoyal7110
0-2=-2
0+2=2
-2=2
So no, its not correct
@@adityagoyal7110 aah yes 0 - 2 = 0+2 which would imply or -2 = 2
@@adityagoyal7110 Since when adding or subtracting to 0 gives back 0? Are you implying 0 is infinite?
Using Tiktok is already a signal for the lack of common sense
I hate people who are bad at math, and think they are good at it. Even worse - people who know SOME math and do wrong things on PURPOSE and then brag about it just to get FREAKING COMMENTS OF PEOPLE WHO GET MAD AT THEM BUT DON'T UNDERSTAND THAT THIS IS EXACTLY WHAT THEY WANT
The very FIRST step of the proposed «solution» is totally wrong.
There are NO solution as this define two parallel lines.
Actually, allowing for sufficient inaccuracy, x=infinity.
As
x 》infinity
Then
(infinity+2)/(infinity-2) 》1
Exactly. And -infinity as well.
@@vasiliynkudryavtsev True. Well spotted. 😊
Tis not how infinity works
@@treeNash Ah, yes, and neither is it how infinity DOESN'T work.🙃
Yea I’m no calculus major, but I know enough about (X)’s to put all X’s on one side and everything else that you can on the other. And that gets 0X=-4, which is about as wonky as the first question.
I am sure that if you would stop at 0X=-4, someone would say X = -4/0
@@tundcwe123i mean now that you mention it..... infinity + 2 = infinity - 2.
That is if you consider dividing by zero to equal infinity, and not undefined
@@xanderlastname3281infinity is not a number. Can't work with it like that outside of a limit or other special conditions.
@@Artleksandr ok but it's a concept
If you have infinitely many things (natural numbers), and you simply append 2 numbers (0 and -1) you still have infinitely many numbers
Cardinality hasn't changed
If you them subsequently remove -1 and 0, you still have infinitely many numbers
Sure it's not a "number number" like 5 or 87, but the concept still works
Adding or removing finite elements from an infinite set does not change the cardinality of the set nor the number of elements
Before I watch your video I'm going to say NO SOLUTION.
How can there be ?
This is why i had a high school teacher who said he doesn't like calling it bringing to the other side because it causes confusion like that
You need to be doing the same thing on both sides, so he emphasizes that point in the equality so none of us do such a bjg mistake
My teacher also hated ‘cancel’ for the same reason. There’s no need to invoke any magic!
@@rezwhapDoes that also apply to Twitter?
I will be born tomorrow and i solved this,how could tiktokers not
Happy birthday
2:41 divide by x-2
😊
To be precise, there is no solution in the real numbers or the complex numbers. But there are solutions in other number systems. For example, both the affine extended real number system and the projective real number system has a value infinity, denoted ∞ (or perhaps +∞ in the affine system). We have ∞+2 = ∞-2 = ∞ so ∞ is a solution. I'm sure there are other solutions in other number systems. Perhaps infinite cardinal numbers?
Integers mod 2 has infinite solutions :)
@@liamernst9626 That is an *excellent* answer! I wish I had thought of it. Of course, modulo 4 also works and has the advantage that "2" is still called 2 in that system.
@@rorydaulton6858🤔 this is essentially a question of whether two parallel lines can intersect at one point
@@vdm942no
@@vdm942 Agreed.
The graph also helps. It’s y=x graphed with two different offsets. Intuitively they are parallel and will never cross.
The guy didn’t even check his solutions back by plugging them in
That’s rule #1 for anything you want to know you’re reasonably correct on
I'm sure if the original presenter of this problem and solution had done the check, he would have plugged in the negative value that he obtained on the left side, the positive value on the right, and shown that indeed his solutions work!
The graphical solution is to plot y = x-2 and y = x+2. You will find these are two parallel lines. Since they do not intersect, the original equation has no solution. Also, if you begin with a problem with a first-order polynomial and end up with two distinct solutions, you made a mistake. A first-order polynomial can only have one solution. (A line in the XY-plane can intersect the X-axis one or zero times, no more.)
We have: x = x + 4
Now substitute x into x:
x = (x + 4) + 4
x = x + 8
x = x + 16
…
And similarly this can be done by first subtracting 2 over,
ie, x = x - 4
The only way adding these finite quantities can work without affecting anything is if x is +/- ♾️
“the input is a contradiction: it has no solutions”
The first line is actually saying
+2 = -2
as you can subtract x on both sides.
That's it.
This is wrong. x is obviously {0, 1} in Z_2 (mod 2).
Or 2 in Z_4.
The realization that he came back full circle was hilarious
I was thinking of perhaps having to go complex or something like that, but glad to know that "no solution" was actually the right answer, because I couldn't see it working in the complex plane either.
My favorite subgenre of this is when there are multiple fundamental errors, but the result happens to be correct.
I immediately saw both equations as straight lines with gradient 1 and intercept 2 and -2 (y=mx+c).
So two parallel straight lines; therefore no solution.
Playing with the equation -> x+2 = x-2
Subtract (x-2) from both sides -> x-x+2+2 = 0 -> 4 = 0, which is categorically false so the original equation can't exist.
Now to watch and see what bprp does.
In complex numbers, |x - 2| = |x + 2| is fairly obviously just any purely imaginary number i.e. Re(x) = 0. But that's the only way to get anything even approximating a solution.
My calc teacher in high school was known for saying "your calculus would be fine if your algebra wasn't horrible horrible"
Because he spent so much time going through everything I had an existential crisis where I KNEW that the equation was impossible, and was actively dreading that he was actually going to show a solution that worked somehow and turn my world upside down.
One solution (over the space of functions, not the reals nor the complex numbers) is that x is a periodic function of period 4, such as sin(pi x/2).
x+2=x-2
x=x-4
x/x=x/x-4/x
1=1-4/x
0=-4/x
x=-4/0
x=unsigned infinity
Now let's see if solution correct.
unsigned infinity + 2 = unsigned infinity - 2
unsigned infinity = unsigned infinity
Any real number added to unsigned infinity doesn't change it. Solution is correct.
Was having a breakdown for 4 minutes thinking you were going to come up with a solution.
Had me questioning my answer 😭
Ngl, the screenshot tricked me for a second because I focused on looking at the reply but didn't look back up at what he was solving. So it seemed to make sense until I looked back up and went "wait a minute"
I love how literally every step they take is incorrect in some way
1:10 Gesture erasing? Nice feature 😂
I genuinely didn’t see any issues about the tik tok solution at first, but then I saw the question
x-2=x+2. x-x=4. x(1-1)=4. x(0)=4. x=4/0. x=∞
x -> infinity
Proof: graph or by incomparablity of both variable
Hence no *Real* Solution exists
This is unrelated but could you please explain why x! = 0 has no solutions (even using gamma function in the complex plane).
If you thought about the initial equation even a little, you can easily see how it's ridiculous. What is a number, where you could either add or subtract 2 from it, and the result is still the same? What is a number where it wouldn't matter whether you added or subtracted anything, it's still the same? And there isn't any real solution.
Bro had that much of confidence to say "Easyyyy"
Move x to the left side, we have x-x+2=-2, then 2=-2, contradiction, done.
That tiktok solution is theblitwral definition of "well yes but actually no"
My problem as a mathematic dummy is that I will forever recall the wrong solution but immediately forget the correct one.
First step is already “WHAT?!”
The dividing thing shows that in the limit of x to infinity, you get 1 on both sides. So infinity I guess?
We can prove that equation has no solution
Step 1:- write the equation in this form x+2/x-2=1
Step 2:- apply compendo and dividendo and we get
x/2=1/0
And we all know that 1/0 is undefined
The simplest thing to do is to check your answer by replacing the X with the answer you got. You will immediatly be able to tell the answer makes no sense.
Infinity. Undefined. As X gets larger, you get closer to a solution... but you'll never actually get there.
10E99 -2 is basically the same as 10E99 +2. The difference would certainly would be undetectable to even the most high-precision instruments of measurement in any context.
When you plot those lines they never intersect because they are parallel.
So having that in mind you know already there won't be any solution.
Thats why is very important visualize in your mind the equations first to then plan how to attack the problem.
When you add the X and subtract the other X, there is no way that both side will meet up.
You can't just multiply one side by (x-2) and not the other side.
Judging by the school course - yes. Theres no answer, but if we go deeper X=infinity. That would be college answer.
X+2=X-2 - make+2 to both sides.
X+4=X - divide bith by X
X/X + 4/X = X/X - subtract X/X
4/X = 0
Any number divided by infinity equals 0.
Infinite is a solution!
x + 2 = x - 2
x = ∞:
∞ + 2 = ∞ - 2
∞ = ∞
Never ask for advice or answers from tiktok.
For 4 minutes i thought I was stupid thinking this can't be solved with a solution .. damn
I knew it couldn’t be solved, but watched the whole video just to remember how it was written 😂
“No solution”
I don't know what upsets me more- the fact that the original poster assumed moving the X-2 to the other side would require multiplication by X+2 instead of subtracting from it, or the fact that they EVEN DEFAULTED TO IT OVER DIVISION
The same goes to Facebook reels, a lot of times some random math questions pop up and the answer is wrong
Put aside the first step, I think developing the expression (x+2)(x-2) is also quite shocking, as the null product tells us that x+2=x-2.
It’s like taking (3x+8)(x-1)=0, developing it and using the quadratic formula, it is just dumb.
For those who do not understand, if you draw 2 linear graphs, one for x+2 and one for x-2, you will see that they will never cross each other. The 2 graphs will always be 4 units apart from each other vertically. That's why x+2 is not equal to x-2
Graphs are always a great way to visualize basic equations.
x+2=x-2
x+2-x+2=0 At this point, I almost said "all real numbers" then I realized that's a PEMDAS issue. Actually:
x-x=0, 2+2=4
0=4, therefore no solutions.
I object to dividing both sides by x-2 so carelessly. You need to allow for the possibility that x-2=0, which means you need to divide the problem into cases, one where x-2=0, and the second case where it isn't zero and you can go ahead and do the division. Of course, that doesn't really help, but at least be rigorous in failure to solve the problem!
I always like to overdramatize when there is no solution.
It's depressing that it takes seconds for a fool to spout nonsence, but it takes so much longer foe experts to explain why this was nonsence.
"x+2=x-2"
"Nuh uh"
I simply moved all the variables to the left and the numbers to the right just like you and got:
x-x=-2-2
0=-4
-4 cannot equal 0 so the equation has no solution.
As a physicist, I would say this has infinitely many approximate solutions: any number that is significantly larger than 2 😀.
(x+2)/(x-2)=1
Lim{(x+2)/(x-2)=1} as x-> - or + inf
(1+0)/(1-0)=1 or (1-0)/(1+0)=1
Therefore X is - or + infinity
I only need to add *1 Marker line* to make the Formula actually work
I knew the TikTok answer was wrong first look. Didn't trust myself on no solution though. Glad to see that was the answer though!
The ans is infinity
Or negative infinity -♾️
I cant stop laughing. then remember I have kids. now I am affraid.
All math teachers drilled us to always check the result, substitute x and calculate both sides of equation whether they are equal. They teach that no more?
Stupid mishaps like this happen all the time, check is not optional.
Plug the supposed solutions back into the original equation and it’s shown to be false.
Can you teach me how can I sove this problem, please?
sqr(a)+sqr(ab)+sqr(abc)=12
sqr(b)+sqr(bc)+sqr(abc)=21
sqr(c)+sqr(ac)+sqr(abc)=30
Find: (a^2 + b^2 + c^2)
Tried but couldn’t solve it. I’d love a video on this problem
(a^2 + b^2 + c^2) is below the first three equations and on the right side of 'Find:'. Thanks me later.
There's probably a better approach but you could solve it by brute force. I suggest substituting √a, √b and √c by u, v, and w just to get rid of the square roots.
You'll then get this system of equations:
u + uv + uvw = 12
v + vw + uvw = 21
w + uw + uvw = 30
Three equations with three variables should yield solutions.
Then, plug the solutions into the last term. (Just remember that it will have to be u⁴ + v⁴ + w⁴.)
I had WolframAlpha do the work for me. There are three sets of solutions. the sum of squares that we are supposed to find can be either 2433, 10002, or 312688557441/384160000.
Like I said, maybe there's a better way but the old-fashioned way should work.
If I had to do it by hand, I'd start by subtracting the second from the first equation:
u + uv - v - vw = -9
We can isolate u by factoring it out and bringing the other stuff on the right hand side:
u (1+v) - (v+vw) = -9
u = (v+vw+9) / (v+1)
it took me some time and I must have made a mistake in my regular scholarly attempts, but then it jumped at me: it works for a = 1, b = 1, c = 100, so your result is 10002.
method: first substitution for those ugly sqrts: A = sqrt(a), B = sqrt(b), C = sqrt(c), so you get
A + AB + ABC = 12
B + BC + ABC = 21
C + AC + ABC = 30
now you see every next equation is 9 bigger, so it is as if you subtract 1 and add 10. and this really works if A = 1, B = 1, C = 10 so you get
1 + 1 + 10 = 12
1 + 10 + 10 = 21
10 + 10 + 10 = 30
A^4 + B^4 + C^4 = 1 + 1 + 10000 = 10002
@@popularmisconception1 Thank you, I liked your idea, but you found the answer by guessing.. Can we solve it by mathematical steps?
I mean my instinct was to move everything to 1 side so (x+2)-(x-2)=0
Which is... x+2-x+2=0
Which is 4=0
And i was confused what is the actual solution, but i guess am not that stupid after and and there is none
Like what do you mean the answer is not somehow i³+5/3?
I did it by adding 2 to both sides, giving me X + 4 = X, which is also clearly impossible.
What if we square both sides, we have fake solns
In a ring of integers modulo 2, 2=0 therefore x=x, so 0 and 1 are the solutions
I added two to both sides and subtracted X from both sides, got 4=0. Still complete nonsense.
So youre telling me he's confident enough that he got the steps right but didn't bother checking to see if the answer he got fits back into the original equation... Thats some beginner level algebra.
I was going to say X = Root(4) = 2, -2
X+2 = X-2
Root(4) + 2 = Root(4) - 2
(-2) + 2 = (+2) -2
0 = 0
Which, of course, is wrong, since if X = Root(4) you'd --either-- have to solve twice for 2 on both sides and -2 on both sides resulting in two answers:
4 = 0 AND
0 = -4 which are both wrong.
Pretty sure you don't get to cherry pick which answer for Root(4) you use on either side, and pretty sure you can't choose the opposite just to make it work. That's also technically brute forcing, and I'm not sure how mathematicians feel about brute forcing. All I knew is the only way for the answer to possibly be true is for X to be -2 on the left and +2 on the right, and the only way to get 2 and -2 to be true at the same time is Root(4).
Always check your answer. OP could see that he messed up somewhere by concluding that 4=0
First off it has no solution, and then the comment under it has a “solution” that not only has almost nothing to do with the question, it’s also just bad…
x=x+a is always false, where a is a complex number not 0
I prefer to have my students think about the problem. I would ask can you think of a number that when you add 2 to it or subtract 2 from it you get the same result. The answer is obviously no and hence no solution.
There is also obviously no number that sin(x) = 2, and yet there are interesting complex solutions