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Mathematics 15 Online
OpenStudy (anonymous):

vertical asymptotes

OpenStudy (anonymous):

Use graphs and tables to find the limit and identify any vertical asymptotes of \[\lim_{x \rightarrow 7}1/(x-7)^2\]

OpenStudy (anonymous):

@zepdrix I need you again! these asymptotes are really throwing me off... you probably hate me by now :(

zepdrix (zepdrix):

\[\Large \lim_{x\to7}\frac{1}{(x-7)^2}\] Graphs and tables? Hmm.

OpenStudy (anonymous):

Yeah!! isn't that a weird question??? LOL wth

zepdrix (zepdrix):

This is something you'll want to get comfortable with.\[\Large \frac{1}{x}\]Look at the above expression. As x gets closer to zero (let's say from the right), the term is getting closer and closer to infinity. Here is how that works. Let's plug in a value really close to zero and see what happens.\[\Large x=\frac{1}{999999} \qquad\qquad \frac{1}{x}\qquad=\qquad\frac{1}{\left(\dfrac{1}{99999}\right)}\]Remember what we do when we divide fractions? We flip the bottom one.\[\Large =\frac{99999}{1}\]Which is a really big number, heading towards infinity.

zepdrix (zepdrix):

I know ^ that isn't exactly what you're looking for, but it's kind of important to understand if you want to get a grasp on asymptotes.

zepdrix (zepdrix):

So for our problem here.. hmm

zepdrix (zepdrix):

Let's just do the cheater way I guess.. let's make a table :3

zepdrix (zepdrix):

We'll make a table, choosing like... 3 values on the right, getting closer and closer to x=7 each time. Then we'll choose 3 values on the left, getting closer and closer to x=7 each time.

zepdrix (zepdrix):

|dw:1376682510179:dw|

zepdrix (zepdrix):

So what we're doing is, we're imitating the limiting process ourselves. We're going to plug in values and see what happens as we get closer and closer.

OpenStudy (anonymous):

ok cool so if we plug that in we get 100!

zepdrix (zepdrix):

|dw:1376682694853:dw|Ok good, let's get a little bit closer to 7 with our next value.

OpenStudy (anonymous):

ok 10000 :D

zepdrix (zepdrix):

|dw:1376682844235:dw|Sounds good, let's get really really close now :3

OpenStudy (anonymous):

100000000 :D

OpenStudy (anonymous):

omg haha

zepdrix (zepdrix):

|dw:1376683038998:dw|Ok good :) so we've determined that when we approach 7 from the right side, we're approaching positive infinity, right?

OpenStudy (anonymous):

LOL bajilion xD and Yeah we are approaching infinity and 6.9 gives us 100 too!?

zepdrix (zepdrix):

positive 100? :OO that's weird!!|dw:1376683417924:dw|

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