## Friday, August 31, 2007

### Junk Drawer Math Problems

from drunkenpanda (HT TAR ART RAT)

philq said...

Not to be pedantic, but the top equation is wrong. If x is a tiny bit above 8, then the fraction is positive, but if x is a tiny bit below 8, then the fraction is negative. While the absolute value approaches infinity, the actual function is near both positive and negative infinity. So the limit doesn't exist.

If the bottom is changed to (x-8)^2 then it's correct. Or you can take a one-sided limit by putting a tiny + or - to the right of the 8. :)

Ithaca said...

No! No! Be pedantic! (But I am not convinced that such an artifact could not surface in a junk drawer.)

philq said...

I debated whether pedantry was acceptable on this blog, but then I rembered your post on greek typesetting in Mr Eliot's Sunday Morning Service :)

Kweku said...
This comment has been removed by the author.
hassan said...

Funny, I was just thinking the same thing - as x approaches 8, from where is it coming?