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Mathematics
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OpenStudy (el_arrow):
find the limit, if it exists, or show that the limit does not exist
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OpenStudy (el_arrow):
limit (x,y)--->(0,0) xy^2cosy/x^2+y^4
OpenStudy (el_arrow):
i did the y path where x=0 and i got lim (0,y)--->(0,0) cosy/y^4
OpenStudy (zarkon):
try \[y=\sqrt{x}\]
OpenStudy (el_arrow):
okay let see
OpenStudy (el_arrow):
i got (x^2*cosy)/2x^2
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OpenStudy (zarkon):
yes...simplify and take the limit
OpenStudy (el_arrow):
okay i got lim y-->0 cos(0)/2 = 1/2
OpenStudy (zarkon):
and what did you get as a final answer when you let x=0
OpenStudy (el_arrow):
i got 1/0
OpenStudy (zarkon):
no
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OpenStudy (el_arrow):
its wrong?
OpenStudy (el_arrow):
i made a mistake its 0
OpenStudy (zarkon):
\[\frac{xy^2\cos(y)}{x^2+y^4}\]
let x=0
\[\frac{0y^2\cos(y)}{0^2+y^4}\]
\[=\frac{0}{y^4}=0\] for all y not zero
OpenStudy (zarkon):
good...is 0 equal to 1/2
OpenStudy (el_arrow):
nope so its DNE
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OpenStudy (zarkon):
correct
OpenStudy (el_arrow):
thank you
OpenStudy (el_arrow):
@Zarkon how did you know to use y=sqrt(x)? is there something that tells what to use?
OpenStudy (zarkon):
it made the denominator have two x's that had the same power so I could combine them...among other things
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