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Thread: First Year Mathematics B (Integration, Series, Discrete Maths & Modelling)

  1. #51
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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by leehuan View Post
    Oh my bad I dropped a negative in that line which I later reintroduced. But wait

    Factoring -v out I have

    1 + 2/(1+v^2) = (1+v^2+2)/(1+v^2) = (3+v^2)/(1+v^2) right?


    Sent from my iPhone using Tapatalk
    Correct!
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    Re: MATH1231/1241/1251 SOS Thread



    But then.. Damn so I do have to p.f. it don't I haha


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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by leehuan View Post


    But then.. Damn so I do have to p.f. it don't I haha


    Sent from my iPhone using Tapatalk
    Yeah.

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    Re: MATH1231/1241/1251 SOS Thread

    I've got a formula here for the normal vector to the surface:

    <Fx(xo,yo), Fy(xo,yo), -1>

    but then somewhere else I see them using this:

    <-Fx(xo,yo), -Fy(xo,yo), 1>

    Which one is correct?
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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by Flop21 View Post
    I've got a formula here for the normal vector to the surface:

    <Fx(xo,yo), Fy(xo,yo), -1>

    but then somewhere else I see them using this:

    <-Fx(xo,yo), -Fy(xo,yo), 1>

    Which one is correct?
    We can use either for the normal, because those two vectors you've written are just negatives of each other, which means they are both valid normals (remember, two vectors that are just multiples of each other will both be valid direction vectors for a line).
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    Supreme Member Flop21's Avatar
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    Re: MATH1231/1241/1251 SOS Thread

    I'm not sure what they want me to enter here. All results I get decimals, after finding the derivative of that integral.

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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by Flop21 View Post
    I'm not sure what they want me to enter here. All results I get decimals, after finding the derivative of that integral.

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    Ancient Orator leehuan's Avatar
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    Re: MATH1231/1241/1251 SOS Thread

    A bit lost in how to incorporate the nominal rate here. Need help with setting up the relevant ODE. I have a formula to find the effective rate for continuous compounding but it's taught in ACTL and not MATH.


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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by leehuan View Post
    A bit lost in how to incorporate the nominal rate here. Need help with setting up the relevant ODE. I have a formula to find the effective rate for continuous compounding but it's taught in ACTL and not MATH.

    Last edited by InteGrand; 9 Aug 2016 at 6:03 PM.
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    Re: MATH1231/1241/1251 SOS Thread

    Lol they made us solve this differential equation by considering how it is an exact ODE. But the solution y=Ax just bugs me... is there a shorter way to doing this one haha


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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by leehuan View Post
    Lol they made us solve this differential equation by considering how it is an exact ODE. But the solution y=Ax just bugs me... is there a shorter way to doing this one haha

    Note the LHS is d/dx (y/x).
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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by InteGrand View Post
    Note the LHS is d/dx (y/x).
    Oops..........................

    That moment when I saw it for this harder one but not the easier one

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    Re: MATH1231/1241/1251 SOS Thread

    divide by e^x cos(y) a bit of rearrange you should get -cot(y)dy=dx



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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by leehuan View Post
    Oops..........................

    That moment when I saw it for this harder one but not the easier one
    Reverse product?
    If I am a conic section, then my e = ∞

    Just so we don't have this discussion in the future, my definition of the natural numbers includes 0.

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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by RenegadeMx View Post
    divide by e^x cos(y) a bit of rearrange you should get -cot(y)dy=dx
    I guess that works too.
    If I am a conic section, then my e = ∞

    Just so we don't have this discussion in the future, my definition of the natural numbers includes 0.

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    Ancient Orator leehuan's Avatar
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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by Paradoxica View Post
    Reverse product?
    Yeah, I'm saying I missed reverse product for the first but saw it for the e^(xy) one
    Quote Originally Posted by RenegadeMx View Post
    divide by e^x cos(y) a bit of rearrange you should get -cot(y)dy=dx
    Final answer ends up with exp(xy)cos(x)=C though

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    Re: MATH1231/1241/1251 SOS Thread

    This is boring and tiring. What is the giveaway as to what values of p and q I am supposed to pick.


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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by leehuan View Post
    This is boring and tiring. What is the giveaway as to what values of p and q I am supposed to pick.

    Remember that d/dz z^n = nz^(n-1), I think that should help you...

    In this case, xy² ???
    Last edited by Paradoxica; 10 Aug 2016 at 9:39 PM.
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    If I am a conic section, then my e = ∞

    Just so we don't have this discussion in the future, my definition of the natural numbers includes 0.

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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by Paradoxica View Post
    Remember that d/dz z^n = nz^(n-1), I think that should help you...
    It's hard to juggle that when I have to consider two constants at a time and not just one

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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by leehuan View Post
    This is boring and tiring. What is the giveaway as to what values of p and q I am supposed to pick.



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    -insert title here- Paradoxica's Avatar
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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by leehuan View Post
    It's hard to juggle that when I have to consider two constants at a time and not just one
    y is on the right, and there is a 3, so you want 3y². x is on the left and you have 4x² so you want 4x³. so xy² is a possibility...
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    If I am a conic section, then my e = ∞

    Just so we don't have this discussion in the future, my definition of the natural numbers includes 0.

  22. #72
    -insert title here- Paradoxica's Avatar
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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by InteGrand View Post


    Andddd this is where intuition collides head on with mechanical rigour...
    If I am a conic section, then my e = ∞

    Just so we don't have this discussion in the future, my definition of the natural numbers includes 0.

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    Re: MATH1231/1241/1251 SOS Thread

    I can't identify the type of this one...



    ...unless I did my partial derivatives wrong

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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by leehuan View Post
    I can't identify the type of this one...



    ...unless I did my partial derivatives wrong
    make dy/dx the subject and you'll see.

    substitution y(x)=x.v(x)
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    Re: MATH1231/1241/1251 SOS Thread

    Quote Originally Posted by laters View Post
    make dy/dx the subject and you'll see.

    substitution y(x)=x.v(x)
    Oh crap I forgot about that g(y/x) because they said they'd give us the substitution in the exam

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