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!

Understanding derivitaves

  1. Apr 4, 2008 #1
    I think I finally figured out derivitaves, but not sure...

    The derivative/differential of x in
    x is 1
    3x + 5 is 3
    5x^2 - 2 is 10

    And breaking down a quadratic thus

    3x^5 + 2x^3 + 5x - 1
    The first derivative is 15x^4 + 6x^2
    The second derivative is 60x^3 + 12x
    Third 180x^2
    Fourth 360x
    And final 360.
     
  2. jcsd
  3. Apr 4, 2008 #2
    No, first and third are wrong.

    1. 15x^4 + 6x^2 + 5
    2. 60x^3 + 12x
    3. 180x^2 + 12
    4. 360x
    5. 360
     
  4. Apr 4, 2008 #3
    The derivative of [tex]5x^2-2[/tex] is actually [tex]10x[/tex].
     
  5. Apr 4, 2008 #4
    Ah...That was the area I had a problem with...The final solitary number...
    Wado (thanks)
     
  6. Apr 4, 2008 #5

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    The derivative (not differential) of 5x2- 2 at at x= 1 is 10. More generally, the derivative of 5x2- 2 at any x is 10x. The differential of x is dx, the differential fo 3x+ 5 is 3dx and the differential of 5x2- 2 is 10x dx.

    The first derivative is 15x4+ 6x2+ 5

    Well, I wouldn't call it "final". That's the fourth derivative. The fifth derivative, and all succeeding derivatives is 0.
     
  7. Apr 4, 2008 #6
    don't you mean the differential of y?

    isn't the differential of x : dx?
     
  8. Apr 5, 2008 #7
    I don't see any
    y's in there. It can be any variable expressed as a function of x.
    I think this is what Halls said also!
     
  9. Apr 5, 2008 #8
    woops
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Understanding derivitaves
  1. Understanding math (Replies: 2)

  2. Don't understand (Replies: 10)

  3. Understanding vectors (Replies: 1)

Loading...