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Homework Help: More derivatives

  1. May 17, 2010 #1
    1. The problem statement, all variables and given/known data

    f(x) = 5e^(2x+1)

    2. Relevant equations

    Chain rule, power rule and constant multiplies rule

    3. The attempt at a solution

    f(x) = 5e^(2x+1) = 5f(x)


    f(u) = e^x f'(u) = e^x
    g(x)= 2x+1 g'(x) = 2

    5f'(x) = 2e^2x+1


    Is that the correct way to go about that?
  2. jcsd
  3. May 17, 2010 #2


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    Homework Helper

    Your answer is correct, but you should write it like this


    u=2x+1, u'
    f(u)=eu, f'(u)=eu

    f'(x)=f'(u)*u' = 2eu=2e2x+1

    So that f(x)=5e2x+1, f'(x) = 5*2e2x+1=10e2x+1

    You used variables like 'u' and 'g' in a confusing manner.
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