Question

Confusing integral. Help!

Answer 1

I have this integral.

Answer 2

Where does dx/(B-1+x) come from??

Answer 3

do you know how to expand ln(x)?

Answer 4

Afraid not..Calculus is not my strong point.

Answer 5

ln(x) is corresponds to x-1 when x tends to 1. in this case they can be replaced to make integral easier.

Answer 6

Where does dx/(B-1+x) come from? I was just picking any value from 0 to 1 and subbing it in

Answer 7

hey, why are you so crazy? put x-1 instead of lnx in the integrand

Answer 8

hey i will get your answer in a moment

Answer 9

Would it not be then dx/B+(x-1) if I did that.

Answer 10

Ok

Answer 11

he did that to take B-1 as one term and make Xf isolated to factor out V0

Answer 12

no he is right trust me

Answer 13

your right

Answer 14

@boothang23 what do u mean no then right!!

Answer 15

I am so confused hahaha

Answer 16

b+x-1 = B-x +x no difference

Answer 17

So the x-1 term is just reversed. B+x-1---->B-1+x

Answer 18

right

Answer 19

as x -> 1, \[\large \dfrac{1}{B + \ln x} \approx \dfrac{1}{B + x - 1}\]

Answer 20

I'm an idiot. This had me confused for a while...

Answer 21

np what is your course

Answer 22

I'm not doing a course...just trying to learn!

Answer 23

what is this formula for

Answer 24

It's formula to work out the time required to concentrate a solute using ultrafiltration.

Answer 25

I

Answer 26

Ideally, you would use solver or wolfram to work this out but the formula I posted is an approximation method.

Answer 27

myself, i rather understanding math more than just get the formula as i can't see through equation to the real world when i didn't understand it.Anyway enjoy your methodology.