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Mathematics 10 Online
OpenStudy (anonymous):

How do I use the squeeze/Sandwich theorem for Multivariable limits?

OpenStudy (zzr0ck3r):

example?

OpenStudy (abb0t):

Same as you did for single variable limits.

OpenStudy (anonymous):

\[\lim_{(x,y) \rightarrow (0,0)}\frac{ xy }{\sqrt{x^2+y^2} }\]

OpenStudy (anonymous):

The lit is indeed 0 but how do I show that using the squeeze theorem?

OpenStudy (anonymous):

limit**

OpenStudy (anonymous):

Lol, Multivarible isn't really THAT hard. It is hard.

OpenStudy (anonymous):

Like what do functions do I take the limit between. How would I know that?

OpenStudy (anonymous):

two***

OpenStudy (jhannybean):

oh you mean your f(x) and your g(x)....

OpenStudy (anonymous):

Yeah. I know how to do it for single variable but not Multivariable.

OpenStudy (zzr0ck3r):

same way I guess, find one you know is for sure smaller and for sure bigger where there limits are equal:)

OpenStudy (anonymous):

How would I know? :P . There are an infinite number of possibilities.

OpenStudy (zzr0ck3r):

same way you know for single variable I guess...

OpenStudy (zzr0ck3r):

im trying to come up with one...

OpenStudy (zzr0ck3r):

are you sure this has finite limit?

OpenStudy (anonymous):

yep.

OpenStudy (anonymous):

According to the textbook this approaches 0.

OpenStudy (anonymous):

Which is true because no matter what curve I choose for a path the limit goes to 0.

OpenStudy (zzr0ck3r):

hmm have you tried many paths?

OpenStudy (zzr0ck3r):

o I C

OpenStudy (anonymous):

How do I exactly pick the two functions? Is there any specific way?

OpenStudy (zzr0ck3r):

assume xy >=0 0=< xy/ √x² + y² <= (x² + y²) / 2√x² + y² -->0

OpenStudy (zzr0ck3r):

do the same thing for xy<0

OpenStudy (anonymous):

Okay. So it just depends on the function I guess?

OpenStudy (zzr0ck3r):

yes for sure

OpenStudy (anonymous):

Thanks :) .

OpenStudy (zzr0ck3r):

np

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