#Integration

1 messages · Page 1 of 1 (latest)

turbid thunder
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How do i solve this question?

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raw bough
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there is no solution

turbid thunder
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the teacher

turbid thunder
raw bough
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defo isnt lol

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that integral has a maximum value of 1 when k is infinity

turbid thunder
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idk this question is from a monash university text book

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k is the upper limit

raw bough
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they've made a mistake then

turbid thunder
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u integrate it and then equate it to 5

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idk what to do after wards

raw bough
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the maximum value of the integral is 1

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there is no solution for k

turbid thunder
raw bough
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no

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the minimum is -infinity

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(no minimum)

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numerically the solution for k would be -1/4, but that would not work because its an improper integral

turbid thunder
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oh yea thats the answer

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not 2

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-1/4

raw bough
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well -1/4 is wrong

turbid thunder
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i thought the top part is always the upper limit

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and the bottom part is the lower limit

raw bough
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are you studying maths at uni

turbid thunder
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foundation

raw bough
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or just doing a maths module

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ah ok

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are you familiar with improper integrals

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like infinity as limits

turbid thunder
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not yet havent touch up on that

raw bough
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ah ok

turbid thunder
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how did u get -1/4 btw?

raw bough
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well in actual fact that has no solutions because the question isnt actually as simple as that

raw bough
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subbing in bounds we get -1/k + 1 = 5

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so k = -1/4

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but its not correct for a few reasons

turbid thunder
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wait u integrate 1/x^2

raw bough
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yes

turbid thunder
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dont u get x^-2

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i mean -1

raw bough
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what

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you get -x^-1

turbid thunder
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cant u bring the x to the top

raw bough
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they are equivalent

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1/x = x^-1

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but you have to remember the negative

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the problem with that integral is that 0 is between -1/4 and 1, so it lies in the interval - but 1/x^2 is not defined for 0

turbid thunder
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right so it would be -x^-1/-1 right ?

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ohh wait

raw bough
turbid thunder
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sorry

raw bough
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so just -x^-1

turbid thunder
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yea

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alright

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thanks