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Mathematics - Algebra & Differential Calculus

Creator: jhoijhoi September 16, 2011 8:24pm
theBMB
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how do you know what week her notes are in?
doof
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theBMB wrote:

how do you know what week her notes are in?

well, im doing the same problem task at uni. i googled the question to confirm i was doing it right. seeing how mab121/126 is only run once, i know what week stuff was taught.
jhoijhoi
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:) Well, as you can see, question one is pretty much done, and question three is... sorta done, lol, have you made progress on question 2?

Maybe we can meet up and study ^^

Do you play LoL too?
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doof
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yeah, catch up could be good. i live in the city. nah, dont play, just found this forum today.

check out this on the "gamma function" http://en.wikipedia.org/wiki/Gamma_function

i could be wrong about laplace transforms.
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ive solved 2. intergrate by parts to give t^(x-1).e^-t + int e^-t.(x-1).t^(x-2)

take (x-1) out the front of the intergral. that leaves (x-1) gamma (x-1)

if you dont get it, let me know. ill scan and upload my solution.
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I've had more help with question 3, how about I upload the answers here, and you upload your answer for question 2?

Together we can simplify the answers into a memorable format ^^




I = Integrate

I t^(x-1)e^(-t)

Integrate By Parts

I U(dV/dx)dx = UV - I V(dU/dx)dx

U = t^(x-1)

V = e^(-t)

= [-t^(x-1)e^(-t)]inf>0 + I e^(-t)t(x-1)t^(x-2)

= [-0^(x-1)e^(-inf)] + I e^(-t)t(x-1)t^(x-2)

= (0-0) + I e^(-t)t(x-1)t^(x-2)

= (x-1) I t^(x-2)e^(-t)

= (x-1) gamma (x-1)







So how do we do part b?
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Guava.
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Math and me...

Is like Scrax and Nukes.

Both makes us go boom... O_o

Thanks to jhoijhoi, Brynolf, Jeffy40hands, Samoh, MissMaw, Vavena, Koksei and The-Nameless-Bard for my signs
jhoijhoi
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bump in case anyone else does university level physics lol ^^
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I'm in high school AP Calculus at the moment but it's always been my strongest subject.

2 seems like doof's process would work - integrate by parts then prove the identity using induction or simple algebraic manipulation.

Unless I'm missing something, b is simple once you've derived A. Since GAMMA(X)=(X-1)(GAMMA (X-1)), you can expand this indefinitely to get GAMMA(X)=(X-1)! which thus establishes the relationship between the two functions for integer values of X.

The question probably wants you to solve it for all values of X, though, meaning that a more thorough definition of "factorial" is necessary as opposed to X(X-1)(X-2)(X-3)...(3)(2)(1) for integer X. In that case, I'm lost, since I haven't done that much higher-level math.

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