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Homework Help: Integration (Substitution)

  1. Sep 6, 2011 #1
    Please help me calculate these integrals.
    Suppose that ∫f(t)dt=11 [0,1]. Calculate each of the following.
    A. ∫f(4t)dt [0,0.25] =

    B. ∫f(1−4t)dt [0,0.25] =

    C. ∫f(3−8t)dt [0.25,0.375] =

    I did the first one and I beleive is right and I try to do the 2nd and 3rd one similarily and can't get them .:uhh:
    u=4t
    du=4dt, or
    dt=(1/4)du
    ∫f(4t)dt [0,0.25]
    =∫f(u)(1/4)du [0,4*0.25]
    =(1/4)∫f(u)du [0,1]
    =(1/4)*11
    =11/4
     
  2. jcsd
  3. Sep 6, 2011 #2
    The second one is almost exactly the same. What substitution would you try??
     
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