Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: How to solve this:f(x)=(x^2) (ln x) (cos x)

  1. Jan 21, 2006 #1
    does anybody knows how to solve this:f(x)=(x^2) (ln x) (cos x) ??

    i would like to know the final answer is it = exp (2/x + 1/x ln x - tan x)??
     
  2. jcsd
  3. Jan 21, 2006 #2

    HallsofIvy

    User Avatar
    Science Advisor

    We can't tell you the answer if you won't tell us the question! I don't know what you mean by "solve f(x)= ". Since you titled this "derivatives" I might guess you mean "find the derivative of f(x)" but in that case your "answer" makes no sense at all. I can only guess that you means something else entirely.

    Please state the question clearly and don't just show an answer, show us how you got it.
     
  4. Jan 21, 2006 #3
    ya,that's the question....myanswer it wrong.May i know how to do it??
     
  5. Jan 21, 2006 #4

    HallsofIvy

    User Avatar
    Science Advisor

    I'll repeat:Please state the question clearly and don't just show an answer, show us how you got it.

    I really doubt that you have a homework problem that says, word for word, "solve f(x)=(x^2) (ln x) (cos x)". It makes no sense to say "solve" a function.

    Now, how did you attempt to do this problem?
     
  6. Jan 21, 2006 #5
    Do you know that d(uv)/dx = v(du/dx) + u(dv/dx)
    Now here you have three functions. Can you take two functions as one and then apply the above rule again i.e. apply it two times.
     
  7. Jan 21, 2006 #6

    Ouabache

    User Avatar
    Science Advisor
    Homework Helper

    Have they move teaching about derivatives, to precalculus courses? :confused:
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook