▲ 1265 ▼ Panik (i.postimg.cc) submitted 2 years ago by ickplant@lemmy.world to c/lemmyshitpost@lemmy.world 146 comments fedilink hide all child comments
[–] kicksystem@lemmy.world 18 points 2 years ago (1 child) wait till she finds out that 0.99999... 9's to infinity is the same as 1 permalink fedilink source hideshow 2 child comments replies: [–] KeisukeTakatou@lemmy.world 7 points 2 years ago (1 child) Lmao how about ...99999 = -1? permalink fedilink source parent hideshow 2 child comments replies: [–] ledtasso@lemmy.world 16 points 2 years ago* (2 children) This one has always bothered me a bit because ....999999 is the same as infinity, so when you're "proving" this, you're doing math using infinity as a real number which we all know it's not. permalink fedilink source parent hideshow 4 child comments replies: [–] yetAnotherUser@feddit.de 2 points 2 years ago Yes, you're right this doesn't work for real numbers. It does however work for 10-adic numbers which are not real numbers. They're part of a different number system where this is allowed. permalink fedilink source parent [–] Snazz@lemmy.world 1 point 2 years ago* (1 child) You can also prove it a different way if you allow the use of the formula for finding the limit of the sum of a geometric series on a non-convergent series. Sum(ar^n, n=0, inf) = a/(1-r) So, …999999 = 9 + 90 + 900 + 9000… = 9x10^0 + 9x10^1 + 9x10^2 + 9x10^3… = Sum(9x10^n, n=0, inf) = 9/(1-10) = -1 permalink fedilink source parent hideshow 2 child comments replies: [–] Kruemel@feddit.de 2 points 2 years ago (1 child) But why would you allow it? permalink fedilink source parent hideshow 2 child comments replies: [–] Snazz@lemmy.world 1 point 2 years ago* (last edited 2 years ago) Because you could argue that the series converges to …999999 in some sense permalink fedilink source parent
[–] KeisukeTakatou@lemmy.world 7 points 2 years ago (1 child) Lmao how about ...99999 = -1? permalink fedilink source parent hideshow 2 child comments replies: [–] ledtasso@lemmy.world 16 points 2 years ago* (2 children) This one has always bothered me a bit because ....999999 is the same as infinity, so when you're "proving" this, you're doing math using infinity as a real number which we all know it's not. permalink fedilink source parent hideshow 4 child comments replies: [–] yetAnotherUser@feddit.de 2 points 2 years ago Yes, you're right this doesn't work for real numbers. It does however work for 10-adic numbers which are not real numbers. They're part of a different number system where this is allowed. permalink fedilink source parent [–] Snazz@lemmy.world 1 point 2 years ago* (1 child) You can also prove it a different way if you allow the use of the formula for finding the limit of the sum of a geometric series on a non-convergent series. Sum(ar^n, n=0, inf) = a/(1-r) So, …999999 = 9 + 90 + 900 + 9000… = 9x10^0 + 9x10^1 + 9x10^2 + 9x10^3… = Sum(9x10^n, n=0, inf) = 9/(1-10) = -1 permalink fedilink source parent hideshow 2 child comments replies: [–] Kruemel@feddit.de 2 points 2 years ago (1 child) But why would you allow it? permalink fedilink source parent hideshow 2 child comments replies: [–] Snazz@lemmy.world 1 point 2 years ago* (last edited 2 years ago) Because you could argue that the series converges to …999999 in some sense permalink fedilink source parent
[–] ledtasso@lemmy.world 16 points 2 years ago* (2 children) This one has always bothered me a bit because ....999999 is the same as infinity, so when you're "proving" this, you're doing math using infinity as a real number which we all know it's not. permalink fedilink source parent hideshow 4 child comments replies: [–] yetAnotherUser@feddit.de 2 points 2 years ago Yes, you're right this doesn't work for real numbers. It does however work for 10-adic numbers which are not real numbers. They're part of a different number system where this is allowed. permalink fedilink source parent [–] Snazz@lemmy.world 1 point 2 years ago* (1 child) You can also prove it a different way if you allow the use of the formula for finding the limit of the sum of a geometric series on a non-convergent series. Sum(ar^n, n=0, inf) = a/(1-r) So, …999999 = 9 + 90 + 900 + 9000… = 9x10^0 + 9x10^1 + 9x10^2 + 9x10^3… = Sum(9x10^n, n=0, inf) = 9/(1-10) = -1 permalink fedilink source parent hideshow 2 child comments replies: [–] Kruemel@feddit.de 2 points 2 years ago (1 child) But why would you allow it? permalink fedilink source parent hideshow 2 child comments replies: [–] Snazz@lemmy.world 1 point 2 years ago* (last edited 2 years ago) Because you could argue that the series converges to …999999 in some sense permalink fedilink source parent
[–] yetAnotherUser@feddit.de 2 points 2 years ago Yes, you're right this doesn't work for real numbers. It does however work for 10-adic numbers which are not real numbers. They're part of a different number system where this is allowed. permalink fedilink source parent
[–] Snazz@lemmy.world 1 point 2 years ago* (1 child) You can also prove it a different way if you allow the use of the formula for finding the limit of the sum of a geometric series on a non-convergent series. Sum(ar^n, n=0, inf) = a/(1-r) So, …999999 = 9 + 90 + 900 + 9000… = 9x10^0 + 9x10^1 + 9x10^2 + 9x10^3… = Sum(9x10^n, n=0, inf) = 9/(1-10) = -1 permalink fedilink source parent hideshow 2 child comments replies: [–] Kruemel@feddit.de 2 points 2 years ago (1 child) But why would you allow it? permalink fedilink source parent hideshow 2 child comments replies: [–] Snazz@lemmy.world 1 point 2 years ago* (last edited 2 years ago) Because you could argue that the series converges to …999999 in some sense permalink fedilink source parent
[–] Kruemel@feddit.de 2 points 2 years ago (1 child) But why would you allow it? permalink fedilink source parent hideshow 2 child comments replies: [–] Snazz@lemmy.world 1 point 2 years ago* (last edited 2 years ago) Because you could argue that the series converges to …999999 in some sense permalink fedilink source parent
[–] Snazz@lemmy.world 1 point 2 years ago* (last edited 2 years ago) Because you could argue that the series converges to …999999 in some sense permalink fedilink source parent
