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

What's the indefinite integral?

  1. Aug 19, 2008 #1
    of sin pi x dx

    i thought it would be - cos pi x dx but i think it might be (1/pi) -cos pi x dx
     
  2. jcsd
  3. Aug 19, 2008 #2
    [tex] \int \sin (\pi x)\, \mathrm{d}x =\frac{1}{\pi} \int \sin (\pi x) \, \mathrm{d} (\pi x)[/tex]

    Does this help?
     
  4. Aug 19, 2008 #3
    yea a lot thanks, i guessed right but i didn't know if i was right
     
  5. Aug 19, 2008 #4
    just wondering why is it 1/pi, i'm not even sure why
     
  6. Aug 19, 2008 #5

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    What is the derivative of cos(pi x)?
     
  7. Aug 19, 2008 #6
    it's - sin (pi x)
     
  8. Aug 19, 2008 #7
    To integrate [tex] sin( \pi x) dx [/tex] consider doing a substitution of [tex] u = \pi x [/tex] then substitute in the appropriate expression of dx in terms of du.
     
  9. Aug 20, 2008 #8

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    Well, there is you problem then: it isn't. Use the chain rule.
     
    Last edited: Aug 20, 2008
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: What's the indefinite integral?
  1. Indefinite integral (Replies: 3)

  2. Indefinite integral (Replies: 5)

  3. Indefinite integral (Replies: 1)

  4. Indefinite Integration (Replies: 1)

Loading...