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Homework Help: Single variation math help

  1. Sep 17, 2010 #1
    1. The problem statement, all variables and given/known data
    s varies directly as r and inversely as t. s=10 when r=5 and t=3. What value of t will s=3 and r-4?



    2. Relevant equations
    Direct variation: y=kx; Indirect variation: y=k/x



    3. The attempt at a solution
    I tired s=kr=k/x and plugging in the given, but I could not get t in the end.

    My real question is how to combine variations, meaning: because s varies directly AND inversely, how do you combine the variations?
     
  2. jcsd
  3. Sep 17, 2010 #2

    statdad

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    Re: Variation

    Write everything as a single variation, using only one constant [itex] k [/itex] rather than two separate expressions.
     
  4. Sep 17, 2010 #3
    Re: Variation

    Got it, thanks.
     
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