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Dido525
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Find the values of a and b so that the following is true.
 2 years ago
 2 years ago
Dido525 Group Title
Find the values of a and b so that the following is true.
 2 years ago
 2 years ago

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Dido525 Group TitleBest ResponseYou've already chosen the best response.0
I am thinking about L'Hospital's rule but I am not sure how I would apply it...
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
well, you can separate them, then solve them
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
Yeah.... But I have two variables then.
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
are you sure it tends to infinity?
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
why two variables?
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
if you differentiate the variable you get nothing from a, but b will still be present, you can get b right?
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
\[\lim_{x \rightarrow 0} (\frac{ \sin(2x) }{ x^3 }+a+\frac{ b }{ x^2 })=0\]
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
Yeah. I think you are right.
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
ahhh, so it tends to zero?
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
Yep :P . I typed wrong.
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
no problem, you can separate them then do the limits, you can spot it by inspection, very easily
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
Hmm Let me try...
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
have you done it?
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
I can't solve the limit of: \[\lim_{x \rightarrow 0}\frac{ \sin(2x) }{ x^3 }\]
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
you can!! differentiate 3 times until the denominator is 1,
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
not 1, differentiate until the denominator is a constant
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
sin(2)=2sin(x)cos(x)
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
I got 4/3 .
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
sin(2x)/x^3 as x tends to infinity?
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
lol!!! im losing it today...
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
but still, i would have thought it was zero
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
The Limit is infinity..... :( .
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
We can't solve anything then.
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
we could, i mean if one of the variables was infinity
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
But We can't do anything with infinity.... It's not a number.
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
wait are you sure it should tend to 0?
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
Well I would assume it should tend to a finite value.
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
i suspect the limit should tend to infinity then for it so satisfy the limit
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
not necessarily, it can be infinity, let assume it was infinity, then we can do the question with ease. have you done analysis by any chance?
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
Here is the question.
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
okay, no problem, assume it is infinity because i think you were right the first time round, if it was infinity just plug in infinity to the differential you had computed
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
If we did that then a would be infinity and b would not exist.
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
b would, it would be x^2,
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
but since b^2 tends to infinity the whole thing would be 0.
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
x^2 sorry not b^2.
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
which would be 0, at when b/x^2 as x >0
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
Exactly. We can't work with that.
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
we could, if b = 0,
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
0/anynumber = 0
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
But it's not. B/x^2 is zero, not b.
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
We don't know what b is.
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
a could be infinity, then this would satisfy the limit
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
But infinity infinity is not 0.
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
No it's not. Infinity is not a number. It's a concept.
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
that is true, i moment, i am trying to multi task, i jst remembered the proof that it isnt,
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
http://en.wikibooks.org/wiki/Calculus/Infinite_Limits/Infinity_is_not_a_number
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
okay, you need to apply l'hpitals rule over and over again, i would recon, but first you need to put all the equation under one common factor so \[=\frac{\sin(2x) + ax^{3} + bx}{x^{3}}\]
 2 years ago

Rezz5 Group TitleBest ResponseYou've already chosen the best response.0
http://answers.yahoo.com/question/index?qid=20110406112720AARpKn1 here is a better and easier way of doing it the sint is taylor expansion i think, the rest is pretty self explanatory
 2 years ago

Dido525 Group TitleBest ResponseYou've already chosen the best response.0
Lol. THanks :P .
 2 years ago
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