#Improper integral

40 messages · Page 1 of 1 (latest)

glacial bronze
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I dont understand the bit where it says that it goes to ln4

versed mossBOT
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glacial bronze
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cus i thought that if x-->infinity then the bottom part is bigger than the top part

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therefore it tends to 0

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but my thinking is wrong

sacred axle
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Oh, wait, it's for infinity.

glacial bronze
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yeah

sacred axle
glacial bronze
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everytime i do these type of questions i always mess up when evaluating the integral like here

glacial bronze
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so i expand the 2t^2 +3

sacred axle
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No need.

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Instead, divide the numerator and denominator by t^4.

glacial bronze
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and compare the 4t^4 with the t^4 on bottom?

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ohhhhhhh

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ok

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so wait if i ever get a question i should divide everything by the highest order of the numerator?

sacred axle
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Well, in general, when evaluating the limits of rational functions, you factor out the highest powers from the numerator and denominator, then cancel.

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Then you're left with a power of t (in this case t^0, since the degrees of numerator and denominator are the same) and an expression with a finite nonzero limit.

glacial bronze
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i sort of understand it i think

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ima try dividing everything by t^4 and see what happens

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1 sec

sacred axle
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Just recall how you did it when studying limits.

glacial bronze
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i think i sort of get it now

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all other terms are bascially irrelevant since it goes it infinity and you divide by t

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is this a valid way?

glacial bronze
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he thought that we already knew it and never did it

sacred axle
# glacial bronze

Well, probably better to write the fraction in the last step as (2 + 3/t^2)^2/(1 + 1/t)^4. Still exact, but you can still see the infinitesimal terms.

sacred axle
glacial bronze
glacial bronze
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but tysm

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+close

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# glacial bronze +close
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# rose adder

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# rose adder
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