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Homework Help: 2 Differentiation Rule Questions HELP

  1. Nov 2, 2004 #1
    Ok here are the questions....
    1)Find the Parabola with equation y=ax^2 +bx +c that has slope 4 at x=1, slope -8 at x=-1 and passes through the point (2,15)


    2)A manufacturer produces bolts of a fabric with a fixed width. The quantity q of this fabris that is sold is a function of the selling price p, so we can write q=f(p). Then the total revenue earned with selling prince p is R(p)=pf(p).
    a) What does it mean to say that f(20)= 10 000 and f`(20)= -350 (f prime) ???
    b) Assuming the values in part (a), find R`(20) and interpret your answer.


    I need help!

    thanks
     
  2. jcsd
  3. Nov 2, 2004 #2

    Pyrrhus

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    Homework Helper

    For the first problem

    Use what you are given if the parabole goes throught the point (2,15)
    then when its x=2. its y = 15. You know the slope is the first derivative right?, make your system of equations.

    For the second problem,

    Understand what the first derivative means.
     
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