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

Still that problem.

  1. Jan 14, 2005 #1
    Well, Sorry but I couldn't find help @ Homework section, I try out here:
    Ok, they tell me to find a and b so that the function:
    f(x)= *Root(2-x^2) if -root(2)<=x<=1
    *x^2 + ax + b if x>1
    has derivative at 1
    I got that the condition for this graph to be continous at 1 is a+b=0
    And I moved to check out the derivative stuff:
    When x->1+, the derivative is 0
    But when 1->1-, igot stuck:
    lim (x->1+) of [f(x)-f(1)]/(x-1) = lim (x->1+) of [x^2+ax+b-1]/(x-1)] (from the function at my first post, I got that when x>1, f(x)=x^2+ax+b) How can I figure out the relation between a and b so that I can put it and the one above to an equation?
    Help me please, thanks!
  2. jcsd
  3. Jan 14, 2005 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    What are you expecting? People to answer your question within a few minutes?
  4. Jan 14, 2005 #3
    Sorry, mein Fehler
  5. Jan 14, 2005 #4
    Very sorry. I though there are many guys here in the forums. sorry alot!
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Still that problem.
  1. Still struggling (Replies: 19)