I Learned How to Divide by Zero (Don't Tell Your Teacher)

They say you can't divide by zero. But "they" say a lot of things. It's time to see how to divide by 0.

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Disclaimer: This video is for entertainment purposes only and should not be considered academic. Though all information is provided in good faith, no warranty of any kind, expressed or implied, is made with regards to the accuracy, validity, reliability, consistency, adequacy, or completeness of this information.

#math #brithemathguy #dividebyzero

[BriTheMathGuy]

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[benhbr]

As James Tanton likes to say: We can do anything in math. We just have to live with the consequences.

[hymnodyhands]

I had a math professor who was careful to say, "For the purposes of THIS CLASS, " ... such and so would not or could not be done. That left the door open for me to really appreciate this!

[averageenjoyer]

So basically, if you allow for division on zero, you have to give up some basic algebra rules

[HistorysRaven]

So you mean we can't create a black hole dividing by zero. Fine, I'll go back to the blackboard.

[ashleyberkowitz]

0:15 Wow, I didn't know Ant is such a strong word in math

[huhneat]

"One divided by 0 is undefined."
Me, a blissfully innocent middle schooler: "Why don't we just define it?"

[mathy]

Math is one of the few things that can make adults feel like children again

[oldjoec]

This answer for the 1/0 problem falls under the category of "University Gas". It's an answer that has no utility in the real world. We have NOT been lied to.. When your real-world problem solution boils down to something divided by zero, you know that you have departed reality, and something is wrong with your problem/solution formulation. The word "undefined" captures that pretty well. "Nullity" is an abstract way of saying that, but it's not an "answer" to the division problem.

[mjr]

"Maybe the real question is 'SHOULD we divide by zero?'" is the best conclusion you could have tbh

[teamcons]

Me in Algebra One: I like your funny words magic man

[Happy_Abe]

I can’t tell being this is April 1st if this is a joke or not😂👏🏻

[hetsmiecht]

I now realize just how mathematically accurate NaN actually is in the floating point standard. NaN for life!

[Speakwastaken]

Notice: he never answered the question, the nullity is still not a valid solution, because 0 times the nullity would still be the nullity, so 1 divided by 0 is not the nullity, he’s just thrown a bunch of math Mumbo jumbo in our faces and hoped everyone who had a more comprehensive understanding of this wouldn’t watch the video since they already knew it was bs

[JJ_TheGreat]

7:25 But what is a "nullity"?

[axisepsilon]

I always wanted to learn abstract algebra. Maybe this is a good excuse to order an abstract algebra book with my nullity dollars in my wallet.

[jagula]

4:02
Problem solved. Right?
Vsauce2 (Kevin): WRONG!

[Strakester]

Here's another way to put it:

If you want to define a new set of numbers, you need to show that it's possible to start with already-defined numbers, go into the undefined set, and come back out the other side into already-defined numbers.

If I gain 5 apples and lose 3 apples, I make a net profit of 2 apples. This holds true even if I went into debt because I lost 3 apples *before* I gained 5. This shows we can go into negative numbers and come back out, which means we can define the set of negative numbers.

We know that the area of a triangle is bh/2. Knowing this, we can easily prove that if we have two isosceles right triangles, and we put them together as halves of a new isosceles right triangle, the new triangle has an area equal to the side length of the original triangles. If our original triangles had side lengths of 1, this shows we can go into irrational numbers (since the hypotenuses have lengths of sqrt(2)) and come back out with the rational number 1, which means we can define the set of irrational numbers.

And though I forget the exact formulas involved, imaginary numbers were proven valid the same way. There was some known formula to solve a certain kind of polynomial, but it was found that if instead of just using the formula outright you worked through the *proof* of the formula, you would end up having to evaluate negative numbers under radical signs at some point in the process, even though you might start and end with real numbers.

Conversely, the video demonstrates that the idea of "nullity" swallows numbers like a black hole from which there is no escape, since you have to "give up some rules of algebra" in order to use it. In other words, this new system is demonstrably incomplete and likely has no practical use.

[Speakwastaken]

0:21 no, they didn’t discover you could take the square root of negative 1, they invented a new number to allow us to, before that you couldn’t take the square root of negative 1, similar to how before they invented calculus you couldn’t do calculus

[青君-bi]

Well, if we set up the "nullity"=b . Then b=1/0.If that's the case, Then b×0=1.Then multiply both sides by an algebra:a.It becomes b×0×a=1×a.On the left, first calculate 0×a=0.b×0=a.If b×0=a, then b×0 is also=1.Which means 1=a.That means every number is equal to one.