1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Differentiation (Trig Function)

  1. Oct 9, 2008 #1
    2. Relevant equations

    Take the second derivative of:

    3. The attempt at a solution


    dy/du = -sin(u)
    du/dx = 2x

    dy/dx= -2xsin(x^2)

    I don't know how to begin taking the derivative of this a second time...
  2. jcsd
  3. Oct 9, 2008 #2


    User Avatar
    Gold Member

    What rule do you think you will need to use?
  4. Oct 9, 2008 #3
    Use the product rule with -2x and sin(x^2). You'll have to use the chain rule again when you calculate the derivative of sin(x^2).
  5. Oct 9, 2008 #4
    So I'd have 2xcos(u) + -2sin(u)

    How am I to use the chain rule at this point?

    Ugh I don't understand how combine rules with composite functions.
  6. Oct 9, 2008 #5

    Solution should be as follows:

    dy/du= sin(u)
    du/dx= 2x

    -2xsin(u) + -2xsin(U)

    -2xcos(u) + -2sin(u)

    = 2x(-2xcos(x^2) + -2sin(x^2))

    Could someone please confirm? Thank you for the help.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Differentiation (Trig Function)