#How to solve asymptotes using limits

36 messages · Page 1 of 1 (latest)

viral flintBOT
main fogBOT
#

Bennxy

undone elbow
#

Hello, you have to take the limit as x approaches ∞

#

In this case, the limit doesn't converge, so there are no horizontal asymptotes

blazing dock
#

But Wolfram says that there is a oblique asymptote

#

How did we get that?

viral flintBOT
#

How to solve asymptotes using limits

frozen grove
#

An oblique asymptote is not a horizontal asymptote. To find an oblique asymptote, you need to write f(x) = mx+ b + g(x) where g(x) has a horizontal asymptote of y=0. Then y=mx+b is the oblique asymptote.

#

Fortunately, f(x) is already written that way for us, so you can just read off the oblique asymptote.

blazing dock
#

Ohh ok but when we used the limit for f(x) why didn't we divide 25x by x?

frozen grove
#

The 25x is separated by the plus sign.

blazing dock
#

So you mean this when we use limits to find the oblique asymptote?

#

$25x + \lim_{x \rightarrow \infty}20\cdot\frac{\left(\frac{50}{x^2+1}\right)}{x}$

main fogBOT
#

Bennxy

blazing dock
#

Do we only apply the limit at infinity for the fraction, and not to other terms?

undone elbow
#

Yes, and it approaches 0

coral dome
#

i think it applies to all terms

undone elbow
# undone elbow Yes, and it approaches 0

Follow what O Dog said. In this case, you have separated the linear term. The rest of the expression approaches 0, so the linear term is the oblique asymptote

#

If you had something like 25x + x², then there's no oblique asymptote because x² approaches inf

blazing dock
#

Aha ok

#

So do we apply the limit at infinity for 25x or not?

#

Because if we do we will get 25*inf

#

Or do we need to divide by x?

#

How does that work?

frozen grove
#

Really, you don't apply the limit at all.

frozen grove
blazing dock
#

Ohh ok

#

I saw this a while ago and thought that we should use the limit over the whole function

#

Does anyone have any resources for this topic?

frozen grove
# blazing dock

That image is the same as what I said. You can do that if you prefer.

blazing dock
#

Hahaha damn sorry man, that image looked more obvious with the functions and stuff

blazing dock
frozen grove
#

Khan academy: oblique asymptotes is my best guess.

blazing dock
#

Ok I'll check it out thanks

blazing dock
#

.close