1. Not finding help here? Sign up for a free 30min 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!

Find the first derivative

  1. Sep 2, 2006 #1
    I've got f(x)=x^2-(7x^2)/2-9x+3

    I need to find the first derivative of it but I get as far as 2x- but I'm stumped as to what to do with (7x^2)/2 Would I use the quotiant rule? Or should I somehow bring the 2 up to the top and if so how do I do that?
     
  2. jcsd
  3. Sep 2, 2006 #2
    If you mean [tex]f(x) = x^2 + \frac {7x^2}{2} -9x + 3[/tex], I'm sure that you can see what the answer will be.

    If on the other hand you mean [tex]f(x) = x^2 + \frac {7x^2}{2 - 9x} + 3[/tex], use quotient rule.
     
  4. Sep 2, 2006 #3
    I guess I risk coming off really stupid but I do mean the first one (7x^2)/2 It looks so simple I know, but i'm not sure which direction to go with the 2. Sorry if I'm wasting your guys' time or anything, but I can't see what the answer should be.
     
  5. Sep 2, 2006 #4
    treat 7/2 as a constant (which it is :)) and get the derivative of x^2
     
  6. Sep 2, 2006 #5
    Oh! Thank you! Funny how the simplest things can seem so hard. I feel silly now.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?