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Homework Help: Help with average value of a function

  1. Jul 23, 2007 #1
    i have a question :cry:
    how would you find a number b such that the average value of
    f(x)= 1+10x-3x^2 on the interval [0,b] is equal to 4.

    i have tried to set this equal to 4 but everytime i try to solve for b i get some number but it is always wrong. please help!!:cry::cry::cry::cry:
  2. jcsd
  3. Jul 23, 2007 #2


    User Avatar

    Staff: Mentor

    Welcome to the PF. How do you calculate the average of a function over an interval? What is the relevant equation?
  4. Jul 23, 2007 #3
    the relevent equation is the f(x)=1+10x-3x^2
  5. Jul 23, 2007 #4
    In order to find the average value of a function over a specified interval [0,b] you must integrate the function on that interval and divide by the interval length.

    Can you formulate an equation which states these facts in terms of b and solve for b?
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