# Graph limits

1. Oct 12, 2015

### Zhang Jiawen

Let f be a function on [0,major infinity] such that for each point in its graph,(x,y)=(y*y,y).At how many points must each point in f have a limit....?

I'm not clear what the question is aiming...

2. Oct 12, 2015

### HallsofIvy

Staff Emeritus
It's a mystery to me! I think "major infinity" must be a translation error but I have no idea what "each point in f has a limit" could mean. In what sense does a point have a limit?

3. Oct 12, 2015

### BvU

Hello Zhang, welcome to PF !

You are not the only one for whom this question is unclear (witness faster typing Ivy's comment!)
My impression is that the problem statement is not quite complete: there remain a lot of questions (some of which may be answered from the context):

Normally functions are a mapping from a domain to an image (or codomain or range).

Your function maps $x \in [0,\infty]$ to what ?
If for each point in its graph x = y^2 that would mean $f: \ x\rightarrow \sqrt x\$ and then the question
can easily be answered with "at infinitely many points", but that probably wasn't intended by the exercise writer. He/she may have had in mind one of several possibilities:
1. for all x in the domain $x \in [0,\infty]$
2. idem, except ....
3. still something else
so my return question is: what is discussed in the section/chapter/episode where this exercise is given ?

By the way: I don't believe this "At how many points must each point in f" is literally quoted ...