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Math Help - Simple function problem

  1. #1
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    Simple function problem

    Hey guys!,
    I've been given a test assignment and there's one really simple problem that I've been staring blindly at for some time now:


    "The distance that a car can travel on 1 litre of gas at the velocity km/h is given by:
    Simple function problem-math1.jpg
    In one hour, driving at a constant speed, the car used 7 litre of gas. How fast was it driving?".




    Now, I know that this is really simple, but I think my brain turned to mush a few hours ago. I've been asked to calculate v, given a function where the value is distance traveled on 1 litre of gas.
    Can anyone give me the first step, please?

    Cheers.
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  2. #2
    MHF Contributor MarkFL's Avatar
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    Re: Simple function problem

    Since this is a test assignment, did your instructor explicitly state that getting outside help is allowed?
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  3. #3
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    Re: Simple function problem

    I think I misused the word "test"! It's not an exam, but a test to prepare us for an upcoming exam and our future homework. So yes, outside help is allowed
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  4. #4
    MHF Contributor MarkFL's Avatar
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    Re: Simple function problem

    I see, in that case, we know that for constant velocity distance equals velocity times time:

    d=vt

    Now, we also have a way to express the distance from the given function:

    d=7\left(\frac{750v}{v^2+2500} \right)

    Now, equate the two, and solve for 0<v, using the given value for t.
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  5. #5
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    Re: Simple function problem

    I see! Thanks mate!
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  6. #6
    MHF Contributor MarkFL's Avatar
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    Re: Simple function problem

    Glad to assist!
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