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    Algebra

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    Ace
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    Algebra

    Post by Ace on Wed May 05, 2010 10:54 pm

    I really need extra credit in my Algebra class, so my teacher told me if I could answer this question, I would get bonus points. Either this question is for Einstein, or I'm missing some sort of equation.
    "A particular disc can be made to rotate at 2 different speeds. If it were made to rotate slower by 135 revolutions per hour, it would require an additional 2.7-hours to make 315 revolutions. Find the higher speed at which it can operate."

    That's all the question says...Could someone help me? Hilarious
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    Ahmed
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    Re: Algebra

    Post by Ahmed on Wed May 05, 2010 11:05 pm

    When do you need the answer by?


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    Re: Algebra

    Post by Ace on Wed May 05, 2010 11:08 pm

    The 10th.
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    Ahmed
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    Re: Algebra

    Post by Ahmed on Wed May 05, 2010 11:16 pm

    I'll work on it this Friday when my brain is emptied of school stress Very Happy


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    Re: Algebra

    Post by Ace on Wed May 05, 2010 11:19 pm

    Thanks man.
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    preid1220
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    Re: Algebra

    Post by preid1220 on Thu May 06, 2010 1:01 am

    no mater how i do this i always get a decimal point, are you sure it didn't say anything else, or perhaps he would be willing to rephrase it?


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    GunMan
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    Re: Algebra

    Post by GunMan on Thu May 06, 2010 12:55 pm

    I'll try to find an answer for you before Monday.


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    Re: Algebra

    Post by Ace on Thu May 06, 2010 5:11 pm

    That's exactly what it says, Preid. Nothing more and nothing less. I don't think the answer would be a decimal, but it might be.
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    Justice
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    Re: Algebra

    Post by Justice on Thu May 06, 2010 5:32 pm

    Is the speed reduced to 135 or the orginial speed is x and the new speed is x-135?
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    Re: Algebra

    Post by Fangy on Thu May 06, 2010 6:02 pm

    It's x-135
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    Re: Algebra

    Post by GunMan on Fri May 07, 2010 7:39 am

    Does this help:

    x = higher speed in rev/hr
    Tf = time for the higher speed to complete 315 rev


    315/x = Tf

    315/ (x-135) = Tf +2.7

    solve simultaneously



    315 / (x-135) = (315 / x) +2.7

    315x / (x-135) = 315 + 2.7 x

    315 x = 315 x - 315 (135) + 2.7 (x^2) - 135 (2.7)x

    2.7 (x^2) - 135 (2.7)x - 315 (135) =0

    2.7 (x^2) - 364 x - 42525 = 0

    use quadratic formula:

    two answers are 209.86 rev/hr and -75 rev/hr

    take the positive answer.


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    Fifi
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    Re: Algebra

    Post by Fifi on Fri May 07, 2010 6:44 pm

    I had Algebra so what i did is make up numbers and place them all around the paper with a bunch of signs and go to the back of the book and take the right answer and put it ina box.. i always get it right and the teacher never caught me! Hilarious


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    Ahmed
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    Re: Algebra

    Post by Ahmed on Fri May 07, 2010 8:08 pm

    Good Job Gman thumbs up


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    Re: Algebra

    Post by Ace on Sat May 08, 2010 3:58 pm

    Thanks Gman.

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