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Homework Help: Word Problems Involving Quadratic Equations

  1. Dec 4, 2005 #1
    hey can you help me solve these, ive got 20 problems..and i only need is this
    problem so that i have an idea of answering the others

    An engineer can decrease by 2 hours the time it takes to travel 200km. If he increases the speed of the freight train by 5km per hour, what is the original speed of the train?
  2. jcsd
  3. Dec 4, 2005 #2


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    Let S be the original speed of the train.

    If he travels a distance of 200km in T hours, can you write down an expression for the speed S ?
  4. Dec 4, 2005 #3


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    Translate the word problem into mathematics. Let's call the original speed of the train v (km/h) and the time it takes t (hours).
    So he travels 200 km in t hours at a speed v:


    If he increases v by 5 km/h, he can travel 200 km in t-2 hours. How would you tranlsate that into an equation?

    Doh, Fermat beat me to it.
  5. Dec 4, 2005 #4


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    Great minds think alike :smile:
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