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

Are these equal?

  1. Aug 8, 2011 #1
    According to Wolfram|Alpha, sometimes, the derivative of arctangent is

    [tex]\frac{d}{dx}\arctan x =\frac{1}{1+{x}^{2}}[/tex]

    and sometimes,

    [tex]\frac{d}{dx}\arctan x =\frac{\arctan x}{x}[/tex]

    So are both of them equal?
     

    Attached Files:

    • EWE.pdf
      EWE.pdf
      File size:
      474.7 KB
      Views:
      117
  2. jcsd
  3. Aug 8, 2011 #2
    The second case is actually
    [tex]\frac{d}{d\times x}\arctan (x)=\frac{\arctan (x)}{x}[/tex].
    :smile:
     
  4. Aug 8, 2011 #3

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    Okay, you have lost me. What does
    [tex]\frac{d}{d\times x}[/tex]
    mean?
     
  5. Aug 8, 2011 #4
    d over d multiplied by x, where d is a constant. Wolframalpha simplifies this to 1/x.
     
  6. Aug 9, 2011 #5
    Oh. So that must have happened the other time too...
     
  7. Aug 9, 2011 #6
    Compare:
    attachment.php?attachmentid=37860&stc=1&d=1312884751.jpg
    Notice the blank between d and x in the left one.
    What input did you give in each time?
     

    Attached Files:

  8. Aug 9, 2011 #7

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    Thanks.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Are these equal?
  1. Help with an equality (Replies: 2)

  2. Euler's equalities (Replies: 5)

  3. What is this equal to? (Replies: 7)

Loading...