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Homework Help: Find the average of f(x)=sqrt(1-x) on the interval [-1,1]?

  1. Jun 10, 2010 #1
    Please show work. There was a negative sign that appeared in the solution and I don't know why.

    I know [tex]\sqrt{}(1-X)[/tex] can be rewritten as (1-X)^1/2 and then you use the power rule to integrate but that gives you

    (1-x)^3/2
    ------------
    3/2

    2(1-X)^3/2
    --------------
    3

    My book shows

    -(1-X)^3/2
    ------------
    3/2

    instead
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jun 10, 2010 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    You integrate that by using the substitution u=1-x. So dx=(-du). Then use the power rule on the u integral. That's where the '-' sign comes from.
     
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