Is 1/0 really infinity, or is it undefined?

[iRaid]

Ok so I was watching this program on TV and the guy ended up getting r=0

With this he put this value into the equation as so:
1/r = 1/0 = infinity


What is up with that? Isn't it undefined.


Also, this is about black holes.

 

[AUK 1138]

it's more proper, and correct, to say 1/r approaches infinity as r approaches zero.

 

[ericksvensson]

Let me guess: Michio Kaku on 'Who's afraid of a big black hole' describing the equation that led to a singularity?. I remember I had the same question.

 

[RCulling]

1/0 is undefined, anything divided by zero is undefined.
But, as AUK 1138 mentioned it is better said that as r tends towards a very small number ( i.e. gets closer and closer to zero ) the fraction will tend towarda bigger and bigger number ( i.e. tend towards infinity ). But at r = 0 the function is meaningless

 

[iRaid]

Why didn't he just do that then rofl. Thanks guys :p