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Lets play math

Discussion in 'Other Off Topic Forum' started by Aureus, Oct 29, 2004.

  1. Aureus

    Aureus Formula 3

    1) find the derivative of (note, Pi as in the greek letter, ie 3.1415……)
    (4e^3x) - 2(x^Pi)^3

    2)Find the derivative of
    Ln(5t)^3

    3) Find all points where the graph of y=2x^(3/2) has a slope of 12.

    4) A rock is thrown straight up with an initial velocity of 128 ft/sec, so that its height (in feet) after t seconds is given by s(t) = 128t -16t^2
    a) When will the rock hit the ground?
    b) what is the rock's velocity when it hits the ground
    c) what is the rock's acceleration when it hits the ground?

    Just a sample of some of the questions from my business calc review sheet.
     
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  3. barranr

    barranr Formula Junior

    Jul 7, 2004
    287
    Herndon VA
    Full Name:
    Rod Barrand
    c) the rock will stop when it hits the ground !

    my head hurts
     
  4. PWehmer

    PWehmer Formula 3

    Oct 15, 2002
    1,733
    Surrounded by Water
    Are you wanting us to do your homework for you?
     
  5. ashsimmonds

    ashsimmonds F1 World Champ

    Feb 14, 2004
    14,185
    adelaide, australia
    Full Name:
    Humble Narrator
    4)
    a) about 8 seconds
    b) the same as when it was thrown
    c) acceleration of an object with no means of transferring energy to produce propulsion is limited to forces applied externally, in the case of a rock (no longer under the influence of our illustrious authors arm) this would be GRAVITY, and so about 9.75 metres/sec (32 something ft), regardless of where it is.

    if however, The Rock's that big bald wrestler dude...

    who cares? he kicks mummy ass. :D
     
  6. mxm

    mxm Rookie

    Oct 27, 2004
    2
    1) 12e^(3x)-6Pi*x^(3Pi-1)
    2) 75/t
    3) +2; -2
    4) look at post above :)
     
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  8. Aureus

    Aureus Formula 3

    Actually I've done them all myself already, (and about 25 additional ones) I'm intersted in seeing what someone else gets for #1 and #2 to check my answer but figured I'd throw in two more for people to play with.


    ashsimmonds... unfortunately while I think that would be the correct scientific answer for 4,c) work with the formula given and not exterior knowledge. While your answer is correct it wouldn't be given credit ;)

    MXM, what are your steps on 2) and 3)? You got different answers than me.

    2)
    f(x) = ln(5t)^3
    = 3ln(5t)
    = 3ln(5) + 3ln(t)

    f'(x) = (d/dt)3ln(5) + (d/dt)3ln(t)
    = 3(1/t)
    = 3/t

    3)
    f(x) = 2x^(3/2)
    f'(x) = (3/2)2x^(1/2)
    = 3x^(1/2)

    12 = 3x^(1/2)
    4 = x^1/2 ............ X^1/2 = square root X, therefor square both sides
    16 = X

    +-16 for slope of 12
     
  9. Noelani

    Noelani Formula Junior

    May 29, 2004
    747
    Full Name:
    R
    I started calc I this year, never having done any pre-calc. Your calc homework is very similar to mine. and i can't do mine either. we should start a study group or something.
     
  10. ashsimmonds

    ashsimmonds F1 World Champ

    Feb 14, 2004
    14,185
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    ah, woopsey, sorry for giving the correct scientific answer. :)

    i totally didn't even notice the formula as the question seemed straight-forward. it's been so long since i had to mess with formula's like that, i can't even begin to care. :)

    what are you doing this crap for anywho?
     
  11. mxm

    mxm Rookie

    Oct 27, 2004
    2
    Yep, my fault. Recalculated both, and got same answers as you.
     
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  13. Aureus

    Aureus Formula 3

    a degree in economics or business requires taking a year of calc ;) But I digress, when I used the gas laws to answer a question about pressure the teacher said "sorry, need to use math, not science." I found it rather humorous actually...

    Noelani, we're in the same boat. I never took pre-calc and took my last math class that used algebra 2 years ago. I'm not only learning calc but I'm stuck re-learning a lot of the old algebraic tricks. But sure if you've got a HW problem you can't figure out feel free to send me a PM, I'll see what I can do with them.
     
  14. jimpo1

    jimpo1 Two Time F1 World Champ
    Silver Subscribed Owner

    Jul 30, 2001
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    Jim E
    Calculus is the only subject I ever failed. :(
     
  15. UroTrash

    UroTrash Three Time F1 World Champ
    Consultant Owner

    Jan 20, 2004
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    I was a physics major for only one semester, now I remember why.
     
  16. Aureus

    Aureus Formula 3

    And yet you still have a ferrari ;) bollocks to calculus eh?
     
  17. sjb509

    sjb509 Guest

    3) Find all points where the graph of y=2x^(3/2) has a slope of 12.

    the derivative dy/dx=3x^(1/2)
    12=3x^(1/2)
    12/3 = 4 = x^(1/2)
    if x=16, 16^(1/2)=4

    The square root of (-16)=4i, where i is (-1)^0.5

    The answer therefore is only x=+16

    Good questions though...
     
  18. Aureus

    Aureus Formula 3

    um, doh?! whoops. Yeah you are correct. Can't believe I missed that... The graph doesn't have anything on the negative side at all. They are all non-real answers.
     
  19. Auraraptor

    Auraraptor F1 World Champ
    Lifetime Rossa Owner

    Sep 25, 2002
    11,491
    MO
    boo I missed this thread. :(
     
  20. normhuff

    normhuff Formula Junior

    Dec 14, 2003
    711
    Peoria, IL
    Full Name:
    J. Norman Huff, Esq.
    Isaac Newton invented calculus and look where it got him...dead...
     
  21. Auraraptor

    Auraraptor F1 World Champ
    Lifetime Rossa Owner

    Sep 25, 2002
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    MO
    LoL!
     
  22. Ferrari0324

    Ferrari0324 F1 Rookie

    Mar 20, 2004
    3,482
    Full Name:
    Brandon
    2+2=4!! As long as I can add up the number of cars I have in my garage, I don't want to do any other math for the rest of my life. Just hoping to get thru this and next semesters stat and accounting.
     
  23. yesod

    yesod Formula Junior

    Nov 2, 2003
    344
    Lakeland,fl
    Full Name:
    Keith
    I am sick of Math. I have taken these math classes over the last couple of years.

    Inter. Algebra
    College algebra
    Pre calc
    Trig
    Engineering Calc I
    Engineering Calc II
    Engineering Calc III
    Differential equations
    Statisitics

    Still have to take computational methods
     
  24. JonBrent

    JonBrent Formula Junior

    Nov 10, 2003
    732
    Heaven on Earth
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    JB
    Actually, in Ferrari math, 2+2=cheaper
     
  25. Auraraptor

    Auraraptor F1 World Champ
    Lifetime Rossa Owner

    Sep 25, 2002
    11,491
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    LoL!!! Awesome.
     
  26. sjb509

    sjb509 Guest

    If you made it through the others OK you'll be fine in computational methods. Forward, Backward & Central Difference methods, Fourier series, all of it builds on what you've already learned, and isn't as difficult as learning the original concepts, IMO.

    If you have time before graduating, a course on Partial Diff Eq, Linear (Matrix) Algebra, and/or Complex Variables, could help you see better how all of the above classes are interelated together and the how some of the monster equations in Mech Eng are formed.

    Good to see another enigineer around.
     
  27. tsang85

    tsang85 Formula Junior

    Mar 5, 2004
    361
    Vancouver
    that stuff is simple. wait till you get to differential equations applications
     
  28. yesod

    yesod Formula Junior

    Nov 2, 2003
    344
    Lakeland,fl
    Full Name:
    Keith
    I didn't have any trouble with any of it.There just so much of it.I am currently taking Statics, Thermodynamics, and Econ.
     

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