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-   -   MathsProblem Solving with Algebra (https://www.askmehelpdesk.com/showthread.php?t=320875)

  • Feb 23, 2009, 03:05 AM
    aloeverahe
    MathsProblem Solving with Algebra
    Can someone help find the equation for this question, the rest i might be able to do afterwards...

    A man cycled a distance of km in hours. For part of the time he cycled a km/h and for the rest at km/h. For how long did he cycle at km/h? Give the answer in its simplest for in terms of

    do you use x and y for this question, because if you do, would: work?

    or if you don't add x and y, would it be: , which therefore ends up as [math] distance = u=L/n-v[/maths]?

    I just want the equation, unless you are willing to give me working out to the equation, then thank you so much!!
  • Feb 23, 2009, 03:50 AM
    sarnian
    Hello Aloeverahe (hmmmm : nice soft skin there ;) )

    As there are two speeds (u and v) with different periods, you have to add L(u) + L(v) to get the total L.
    You should use x for speed u and y for speed v, as these periods are unknown.

    L(u) = ux , and L(v) = vy
    L(u) + L(v) = L
    ux + vy = L
    ux = L - vy

    You want to know the value of x :

    x = (L - vy)/u

    Note that you used Km/hr for speed, so your time is in hours too.


    (u+v)n = L is incorrect as you add here u and v, making the speed higher than either one of them, times the total time period.

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