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Finding the derivative of g(x)

  1. Mar 28, 2012 #1
    1. The problem statement, all variables and given/known data

    Let f(x) be a continuous and differentiable function on the interval 0 ≤ x ≤ 1, and let g(x)=f(3x). The table below gives values of f'(x), the derivative of f(x). What is the value of g'(0.1)?

    http://img845.imageshack.us/img845/442/33806538.jpg [Broken]

    2. Relevant equations

    3. The attempt at a solution

    g(0.1) = f(3(0.1))
    g(0.1) = f(0.3)
    g'(0.1) = f'(0.3)
    g'(0.1) = 1.096

    Did I do the problem correctly? Thanks!
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Mar 28, 2012 #2
    Look correct assuming the picture and problems statement are what you have shown.
  4. Mar 28, 2012 #3
    I think the answer should be E. g'(x) = 3*f'(3x). So, g'(0.1)=3*f'(0.3)=3*1.096=3.288
  5. Mar 28, 2012 #4
    ^ Actually that's correct because of the chain rule (haven't taken calculus in 5 years lol)

    g(x) = f(u), where u = 3x so
    g'(x) = f'(u)du = f'(3x)*3
  6. Mar 28, 2012 #5

    Thank you guys!
    Forgot to use chain rule, thought I could just multiply 3*(0.3)
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