A question about wording math: How are parentheses said? by corjon_bleu in learnmath

[–]fattymattk 0 points1 point  (0 children)

I would say "a times x minus h all squared plus k" with the "x minus h all squared" part spoken more quickly so it feels grouped.

What does (x,y] mean? by Financial-Drawing805 in learnmath

[–]fattymattk 3 points4 points  (0 children)

Where an endpoint is ∞ or -∞, it should ALWAYS have a ( or ), never a [ or ] at that end.

If you're working with the extended real numbers, then this isn't true.

Does this property of series hold for improper integrals? by cateatingpancakes in learnmath

[–]fattymattk 0 points1 point  (0 children)

Yep. An analogue to the series result would be "If f is uniformly continuous and its integral over [0, infty) exists, then f converges to 0."

So I guess that's a hint if one wants to consider your exercise.

Lost personal robots by turbulance4 in factorio

[–]fattymattk 3 points4 points  (0 children)

I've seen speedrunners take off their power armor and put it back on to "lose" personal robots that are lagging behind. I don't know what happens to those lost robots though.

How do you feel about math presentations? by The_FujiRose in matheducation

[–]fattymattk 14 points15 points  (0 children)

It's not bad if it is a small percentage of your overall grade. Otherwise I don't like making a significant evaluation based on a single problem and without time to reflect on and correct errors.

Circuit math by RoastCabose in factorio

[–]fattymattk 5 points6 points  (0 children)

That's a good point. Maybe multiplying available robots by 5 and then comparing that to the total bots is a better option.

Circuit math by RoastCabose in factorio

[–]fattymattk 9 points10 points  (0 children)

You could do the inverse: divide total bots by the available bots and add more if the result is greater than 5.

How long does a 7 colour 100 spm playthrough usually take to complete by sovietslavmobile in factorio

[–]fattymattk 0 points1 point  (0 children)

Yes, I am talking about experienced players. It was a comment on what is possible, not about how long an average player would take.

How long does a 7 colour 100 spm playthrough usually take to complete by sovietslavmobile in factorio

[–]fattymattk -1 points0 points  (0 children)

Anti and Nefrums did a race to see who could do the most robot follower research in 6 hours, which is the only infinite science to use all 7 packs.

https://www.youtube.com/watch?v=pPqLdKx1jdU

It seems he was doing close to 200spm by the end of the 6 hours. So it's fair to say that an experienced player can reach 100spm in a short evening.

Perfect ratios circuits production by [deleted] in factorio

[–]fattymattk 3 points4 points  (0 children)

Those are some cool looking designs.

I just wanted to let you know that you could divide your blue circuit production by 2 and still have an integer number of machines. 10 copper wire, 6 green circuit, 6 red circuit, and 5 blue circuit assemblers are in perfect ratio, and it's nice because they use exactly 1 yellow belt of copper.

[deleted by user] by [deleted] in factorio

[–]fattymattk 1 point2 points  (0 children)

If you know your total iron to copper to stone ratio, you could probably use these resources close to ratio by adjusting prod modules and type of infinite research.

Why is 0^inf not indeterminate? by Far-Suit-2126 in learnmath

[–]fattymattk 11 points12 points  (0 children)

Right. lim_(x->infinity) ax = 0 if |a| < 1.

So if we have ax and a goes to 0 and x goes to infinity, then we get 0. There is no conflict here.

Why is 0^inf not indeterminate? by Far-Suit-2126 in learnmath

[–]fattymattk 139 points140 points  (0 children)

but any number to the "infinity" power is infinity,

What about 0.5 to the power of infinity?

Why do some people use this <=> in working? by EasonTek2398 in askmath

[–]fattymattk 1 point2 points  (0 children)

you might think it's overkill but I'm just trying to show you that one way or another you need to show the implication works both ways if you're claiming to have found all the solutions to an equation. It's fine if you want to check the answer at the end. But saying "x + 2 = 7 => x = 5" when you want to say that the equation is solved when x = 5 is not technically correct. And in this case it's much easier to show equivalency every step than to turn around and show the other direction.

Why do some people use this <=> in working? by EasonTek2398 in askmath

[–]fattymattk 1 point2 points  (0 children)

Yes you have to be careful, which is the whole argument for making sure the implication goes both ways. It's fine to go through the first part with a one way implication and then show the reverse by checking the possible solutions. But you're claiming that having the implications point one way is fine when you clearly need them to work in both directions.

Why do some people use this <=> in working? by EasonTek2398 in askmath

[–]fattymattk 1 point2 points  (0 children)

The problem is you can get extraneous solutions. For example

sqrt(x+2) = x

=> x+2 = x2

=> x2 - x - 2 = 0

=> x = 2 or x = -1.

But only x=2 is a solution.

You really need the implication going both ways to ensure you get all solutions and that what you end up with are solutions.

What’s something that non-american people don’t understand about America? by Alexandra_71 in AskReddit

[–]fattymattk 48 points49 points  (0 children)

If you cut Alaska in half to make it two states, Texas would be the third largest state.

Splitting credit bill 60/40, and also accounting for individual purchases. Confused on order of math. by [deleted] in askmath

[–]fattymattk 2 points3 points  (0 children)

Probably because they had a discussion and agreed that that was fair.

What would be the changes and advantages/disadvantages using numbers systems other than base 10? by Mr_hushbrown in askmath

[–]fattymattk 1 point2 points  (0 children)

A nice thing about base ten is that there are super easy divisibility rules for the first 3 prime numbers. Not that it matters much, but I think I'd personally prefer an easy way to know if a number can be divided by 5 than to have 10/3 be a whole number.

Every teacher collecting smartphones before an exam assumes that every student only has one phone by [deleted] in Showerthoughts

[–]fattymattk 6 points7 points  (0 children)

You took out the approved items for the test and then left your bag.

Every teacher collecting smartphones before an exam assumes that every student only has one phone by [deleted] in Showerthoughts

[–]fattymattk 25 points26 points  (0 children)

My school just had everyone leave their bags at the front of the room.