Spyke
reddthat.com

It’s been a while… but isn’t that negative?

Or is there some default given of which side it’s approaching from.

58
LeFrogreply
discuss.tchncs.de

I think it is not defined. It has a limes from the left (- inf) and limes from the right (+ inf) but no two-sided limes.

Edit: wolframalpha agrees but I don't know for sure

41
dohpaz42reply
lemmy.world

It has a limes from the left… and limes from the right…

Is that the Tootsie Roll Theorem?

18

(Just including the graph for reference. I'm not sure it helps with proper description or the answer the teacher was asking for, but you can see that from one direction it goes negative as you approach 8 and from the other it goes to positive infinity.)

28
lemmy.world

I have a BA in Mathematics. The limit is indeed determined by the direction you approach the limiting value.

When given without specification, the limit is implied to come from the left, meaning it increases towards the limiting value, which is why you see +inf.

13
roorooreply
feddit.org

Yeah but then it should be negative infinite, cause if x<8 the fraction is negative.

16
lemmy.world

Ah, I misread the - as a +. You're correct! Sorry, I just woke up and am in the middle of my morning doomscrolling sesh

12

Conveniently modeled with the same limit.

Though I'm not sure what negative doom is and what happens when it approaches infinity.

5
carmo55reply
lemmy.zip

This is just not true. The normal limit we have here means a limit would have to exist from both directions and they should be equal. They're not, so the limit doesn't exist.

One-sided limits would be denoted by x -> 5– and x -> 5+ or similar.

PS: in complex analysis, there is no distinction between +infty and -infty, so there it would be correct to say the function has limit infty at 5.

6
Epherareply
lemmy.ml

In my experience with maths, there's a whole bunch of different conventions all over the place, so it might've genuinely been how they were taught, even if you were taught differently...

4

Yeah, that's my experience too. When we did this in school we always defined from which side we were approaching the function.

3

You're right. But in this case, which is the case I was referring to, there is no two sided limit. It is discontinuous. It is in this case which I was referring to. Sorry for not being clear.

1
Ooopsreply
feddit.org

It should be +/-∞

Minus or plus depending on the side from which you approach the limes.

12
slrpnk.net

Just here to comment on the weird spreadsheet format (of that oooooold joke)

35
lemmy.nz

I took a screenshot and put it in a word doc and embedded that in a excel sheet and sent it in an email...

"Endorsed for MS Office" on LinkedIn.

8

Don't think so. It looks weird, but very consistently. Look at the kerning, the spacing after each "e" is just a little too wide, and all the "e"s have the same little hump at the top.

I would guess this is a mild anti-dyslexia font or sth like that.

2

or the domain is the projectively extended real line! (obv not the case here ofc)

3
lemmy.world

That’s a ChatGPT kind of answer. A pattern is recognized, but the meaning isn’t understood.

27
chickenreply
lemmy.dbzer0.com

There's no way ChatGPT would be creative enough to put a number on its side

22
AlecSadlerreply
lemmy.dbzer0.com

ChatGPT is such garbage.

edit: The people down voting me clearly are bots or GPT fanbois. In AI circles nobody thinks ChatGPT is good.

16

The first one is incorrect, the limit doesn't exist unless you specify whether you're coming from the left or right.

On another note, I think their student has invented a new symbol for "Does Not Exist".

13

Story time, third grader me would have done this no questions about it.

Having to solve multiplication and recently had learned the table of 9 trick i was looking if there where other tricks I could find.

The first one was number x10 and what i observed is that if you do times ten. You take the number. And you put 1 “0” behind it.

Interesting…. I thought

But the next one multiplied with a single digit so how could i apply that theory.

Simple. 1+0 is 1, which is a single digit so if you multiply by 10, you actually multiply by 1+0 which means you put 1 zeros behind it

Multiple by 2 is short for multiply By 2+0, put 2 zeros behind it

Multiply by 9, put 9 zeros behind it.

I definitely knew this is not what we had learned, and knew there was a “chance” i was going to fail all of these, i also even knew some of the actual answers however i also believed there was a chance that i found an alternative equally good solution, and I consciously decided to take that risk because I wanted to know if i was right. Maybe I discovered something new

My teacher was not happy to say the least, and in that (actual) furry did treat me unfair and it still bothers me. Because i got a zero for the assignment.. while i was very certain that the 2 occurrences of x10 did have the appropriate solution.

4

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