Results 1 to 2 of 2

Math Help - differentiable product of functions

  1. #1
    Junior Member
    Joined
    Oct 2009
    Posts
    39

    differentiable product of functions

    A question asks "If f*g and f are differentiable at a, what conditions on f imply that g is differentiable at a?"

    I am also wondering: if f and g are both NOT differentiable at a, but f*g is differentiable at a, what conditions must apply to f and g? I can think of examples but not a general situation; I am also not sure there is even a "general situation"..
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member
    Joined
    Feb 2010
    Posts
    422
    One possible condition is that f is non-zero in some neighborhood of a, since in that case, you can write g={fg\over f} and apply the quotient rule.

    I'm not sure about the second question, sorry.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Differentiable Functions
    Posted in the Differential Geometry Forum
    Replies: 4
    Last Post: January 9th 2011, 07:13 PM
  2. Replies: 9
    Last Post: December 17th 2010, 08:13 AM
  3. differentiable functions
    Posted in the Calculus Forum
    Replies: 7
    Last Post: January 10th 2010, 10:04 AM
  4. Differentiable functions.
    Posted in the Calculus Forum
    Replies: 1
    Last Post: November 17th 2009, 02:47 PM
  5. Sequence of differentiable functions, non-differentiable limit
    Posted in the Differential Geometry Forum
    Replies: 3
    Last Post: April 3rd 2009, 05:13 AM

Search Tags


/mathhelpforum @mathhelpforum