I had a student tasked with summing a finite geometric sequence with |r|>1, let’s say 1+2+4+8+16. He had apparently forgotten the formula for that, but knew the formula for the infinite series a/(1-r). Good enough he thinks, and sums 1+2+4+… = -1, then subtracts off the excess terms 32+64+128+… = -32, and gets the correct answer of 31.
crwth
- 1 Post
- 14 Comments
crwth@piefed.zipto
Ask Lemmy@lemmy.world•What nursery rhymes and playground songs were popular when you were very young?English
0·27 days agoJingle bells Jingle bells, Santa Claus is dead // GI Joe the Eskimo shot him in the head.
Row row row your boat, gently down the stream // Throw your teacher overboard and listen to her scream.
Mine eyes have seen the glory of the burning of the school // We have tortured every teacher and we’ve broken every rule.
Chinese, Japanese, Dirty knees, Look at these.
crwth@piefed.zipto
No Stupid Questions@lemmy.world•Can a puzzle with missing pieces be considered complete?English
0·1 month agoIf she’s used all the pieces and solved enough to reverse engineer the shape of all the missing pieces, then it is fully solved. If the missing pieces cannot be individually identified due to shared edges, then it is still solved, but is no longer a 1000 piece puzzle and she should only claim to have solved the 999 or 998 piece subpuzzle.
Yes, I switch between a few OTA stations. Usually just on as background noise. There’s a couple of NPR programs that I sometimes try to listen to.
crwth@piefed.zipto
News@lemmy.world•Tennessee high court blocks order allowing media witnesses to view more parts of executionsEnglish
3·3 months agoYou shouldn’t kill anyone in private that you wouldn’t kill in public.
crwth@piefed.zipto
Ask Lemmy@lemmy.world•If you saw a mushroom cloud, what would you say?English
0·3 months agoGet a good look. You might never see another.
crwth@piefed.zipto
No Stupid Questions@lemmy.world•How would you actually tax the ultra wealthy?English
0·3 months agoSo someone with an income of $1M (20A) has a tax liability of $2M, and earning $10M means you owe $200M? At least with traditional tax brackets, it’s hard (but not impossible) to accidently get marginal rates over 100%.
I flooded a dormitory once, but I blame building maintenance for tricking me into it.
I wake up and head to the bathroom. Turn on the shower, nothing happens. Try the sink, still no water. No advance notice to the residents, but the water must have been shut off for some reason. I have a class to go to, so I turn everything “off”, get dressed, and leave. I’d forgotten that one of the sink knobs was threaded the opposite way from the standard convention, so that one was full on when the water was restored. Came back to the dorm after lunch and realized exactly what I’d done as soon as I entered the hallway and saw the maintenance man running his shop-vac outside my room. It overflowed the sink drain, and the bathroom floor drain, flowed through the dorm room, and was in the process of flooding the hallway.
crwth@piefed.zipto
Ask Lemmy@lemmy.world•Is private age verification technically possible and if so how?English
0·4 months ago- Apply for access to age-gated content.
- Ignore application for 18 years.
- Your account has been approved.
crwth@piefed.zipto
Ask Lemmy@lemmy.world•Do you still remember the layout of all the houses/apartments you've lived in? Are there any other places where you still have a "map" of in your head?English
0·4 months agoI think I could do fairly well with any place I’d frequently been in, and with enough autonomy to get disoriented and reoriented. Some of the houses I’ve lived in are not much more architecturally elaborate than a shotgun shack, but I could also do my elementary school, most of a middle school, two college dormitories, and most of a university library.
It’s my favorite opening move in Wordle like games. Screw you vowel lovers with your AUDIOs and OUTIEs.
crwth@piefed.zipto
News@lemmy.world•Legendary Singer Neil Sedaka Rushed to Hospital in Los AngelesEnglish
2·4 months agoHe’s dead.
crwth@piefed.zipto
No Stupid Questions@lemmy.world•How come in American classrooms they make another language an elective. Why not teach our kids as many languages possible that way if we go somewhere we will kind of have uper hand?English
0·4 months agoThe college I graduated from required a year of foreign language for graduation – actually take it and pass, not just test out of it.
OK, that’s not quite true. For some reason, the mathematics department was grouped with the languages for purposes of this requirement, so you could take a year of calculus in lieu of a foreign language if you preferred.
Unless you were a math major. Classes in your major didn’t count, so all math majors absolutely had to take a foreign language.
Unless you were a dual major like math-physics. Dual majors could apply classes from both majors towards distribution requirements. I knew several “math” majors who took just enough physics classes to qualify as a dual major for the express purpose of not having to study a language.


I know a couple of math tricks you can do with playing cards.
Give an audience member a pre-sorted deck of cards. Remove any card. Riffle shuffle the deck 3 times (4 if you’re bold). Return the removed card to a random position in the deck. Magician examines the deck and identifies the card.
Audience member selects any 5 cards and hands them the the magician’s beautiful assistant. Assistant examines these cards, and reveals 4 of them, one at a time, to the magician. Magician predicts the 5th card.