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Mathematics 14 Online
OpenStudy (anonymous):

Find the indicated limit, if it exists.

OpenStudy (anonymous):

OpenStudy (zzr0ck3r):

Its right behind you!

OpenStudy (zzr0ck3r):

all you need to do here is plug in -1 to each expression and make sure they are the same

OpenStudy (anonymous):

So 4-x = 4-1 = 3

OpenStudy (zzr0ck3r):

note: this one is pretty easy because each expression in the piecewise function is defined at x=-1 what we are doing is checking the limit at each endpoint and making sure they are the same. it just happens that it is very easy to check the limit of the endpoints for this function, you just plug in -1

OpenStudy (zzr0ck3r):

we are not looking at 1, we are looking at -1

OpenStudy (zzr0ck3r):

4-(-1) = 5+1 = 5

OpenStudy (zzr0ck3r):

we dont need to check the middle one, because it does not matter.

OpenStudy (zzr0ck3r):

for a limit to exist we only care about the areas around the point, not the point itself

OpenStudy (anonymous):

and x+6 = -1 + = 5

OpenStudy (zzr0ck3r):

yep, so. as we approach -1 from the left we get 5, as we approach -1 from the right we get 5, so the limit is 5

OpenStudy (anonymous):

Thank you, do you mind going through four more problems with me?

OpenStudy (zzr0ck3r):

one more, but this was supposed to be my last. I got to get up in 7 hours:)

OpenStudy (anonymous):

Okay, thank you and my apologies.

OpenStudy (zzr0ck3r):

lol its fine:0

OpenStudy (anonymous):

Use graphs and tables to find the limit and identify any vertical asymptotes of

OpenStudy (zzr0ck3r):

ok do you have the thing graphed?

OpenStudy (zzr0ck3r):

@Loveiskey18 ?

OpenStudy (anonymous):

No, I'm attempting to graph it now.

OpenStudy (zzr0ck3r):

http://www.wolframalpha.com/input/?i=1%2F%28x-4%29

OpenStudy (anonymous):

Okay

OpenStudy (zzr0ck3r):

what y value are we getting if we approach 4 from the left?

OpenStudy (zzr0ck3r):

you looked at -4

OpenStudy (zzr0ck3r):

do you just want the answer or to do the problem?

OpenStudy (anonymous):

The y value is 4^1, right? I want the answer, and the steps it took to get it. If you don't mind

OpenStudy (zzr0ck3r):

ok then look at the graph I posted

OpenStudy (zzr0ck3r):

as our x values get really close to 4 ( coming from the left) what is the graph doing?

OpenStudy (anonymous):

It is curving downards.

OpenStudy (zzr0ck3r):

we know the thing is undefined at x =4, so when we get close to 4 the thing is either shooting off to negative infinite or positive infinity

OpenStudy (zzr0ck3r):

which do you think it is?

OpenStudy (anonymous):

I honestly want to say negative.

OpenStudy (zzr0ck3r):

yep

OpenStudy (zzr0ck3r):

so, you just found the limit using the graph

OpenStudy (anonymous):

So the answer is - (infinite sign) x = 4?

OpenStudy (zzr0ck3r):

\[-\infty\]

OpenStudy (anonymous):

yes.

OpenStudy (zzr0ck3r):

\[\lim_{x\rightarrow 4^{-}}\frac{1}{x-4}=-\infty\]

OpenStudy (zzr0ck3r):

now to solve this with a table we just plug in values for x that are really close to 4(coming from the left) so let x = 3.9, 3.99, 3.99999, 3.999999999999999999 and you will see that its tending to negative infinity

OpenStudy (zzr0ck3r):

do you know that the asymptote is?

OpenStudy (anonymous):

the answer I posted.

OpenStudy (anonymous):

@zzr0ck3r

OpenStudy (zzr0ck3r):

I think you need to go back and study some old stuff. this is just going to get more confusing. you should know what an asymptote is if you are in calculus.

OpenStudy (zzr0ck3r):

google it. hint...its x = something its a number, not -infinitu

OpenStudy (anonymous):

I know what it is, I asked you if -∞ ; x = 4 was the correct answer.

OpenStudy (anonymous):

Well these are my options. ∞ ; x = -4 -∞ ; x = -4 -∞ ; x = 4 1 ; no vertical asymptotes

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