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Homework Help: Find the derivative of the vector function

  1. Feb 23, 2010 #1
    Find the derivative of the vector function r(t) = ta x (b + tc)
    a=<-2,2,-1> b=<-1,1,1> c=<-2,2,4>


    I know r(t)=ta x (b + tc)=(axb)t+(axc)t^2
    then i got lost
     
  2. jcsd
  3. Feb 23, 2010 #2

    tiny-tim

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    Hi xstetsonx! :smile:

    (try using the X2 tag just above the Reply box :wink:)
    ok, now differentiate wrt t. :smile:
     
  4. Feb 23, 2010 #3
    don't know how because they are all numbers. Should i do the cross product or what do i do?
     
  5. Feb 24, 2010 #4

    tiny-tim

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    uhh? everything except t is a constant :confused:
     
  6. Feb 24, 2010 #5

    HallsofIvy

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    Everything except t is a constant vector. t is the only numeric variable in the problem.
     
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