#Limits help needed

54 messages · Page 1 of 1 (latest)

valid wagon
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I need help solving a limit: limit of sin(x)/x as x approaches 0.

white stagBOT
blissful arrow
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it should be 1

twilit radish
valid wagon
valid wagon
blissful arrow
blissful arrow
valid wagon
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how would we use squeeze theorem on that anyway

blissful arrow
valid wagon
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i guess squeeze theorem would work

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if i did it properly

blissful arrow
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wait

valid wagon
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bludicus

blissful arrow
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yes you use the squeeze theorem

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but you can only use trig identities

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right?

valid wagon
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that would be prefferable

blissful arrow
blissful arrow
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because it states that if f(x)<=g(x)<=h(x)

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and f(p)=h(p)

twilit radish
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also you can use 1 as the upper bound but you have to use that |sin x| ≤ |x| for all x

blissful arrow
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then g(p) must also be equal to f(p) and h(p)

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which means their limits are equal

blissful arrow
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the function that is supposed to be less than sin(x)/x is greater at one point

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so you will need a different function

maiden lodge
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use taylor series expansion of sin

or squeeze sin(x) between x and x-x^3/6

valid wagon
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the limit of both functions as they approach 0 is 1

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and their function values at 0 are 1

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at other micro values around 0 and in general, it's either too big or too small

blissful arrow
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which in this case is sin(x)/x

blissful arrow
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but it has to be

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less than or equal to

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or I may be wrong 🤷‍♂️

valid wagon
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i remember it being equal to g(x) at one point but >= or <= at all the other points of the respective graphs

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ngl I don't think it's possible w/o squeeze theorem

twilit radish
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to be sure, are you only allowed to use squeeze theorem & trig identities? see if you can use l'hopital or taylor series

maiden lodge
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Actually, it's solved historically way before l'hopitale's and it's various proofs include a lot of the tools used to prove l'hopitale

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there is a geometric proof too

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n-gons-->circles

valid wagon
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update

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it turns out you can use squeeze theorem

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or just actually find the limit

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by approximation

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how do you end the question

twilit radish
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.solved