1. Limited time only! Sign up for a free 30min personal 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!

Product Rule?

  1. Mar 28, 2010 #1
    My question is how do they transform equation A. into B.. I know they are using the product rule but dont know what is going on.

    EQ A.)D(1/r^2)d/dr(r^2(dC/dr))-kC=0
    now how do they get Eq B.

    EQ B.) (d^2C/dr^2)+(2/r)(dC/dr)-(kC)/D=0
     
  2. jcsd
  3. Mar 29, 2010 #2

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    The derivative of r^2 dC/dr is, by the product rule, [r^2 d(dC/dr)/dr]+ [d(r^2)/dr] dC/dr= r^2 d^2C/dr+ 2r dC/dr. Multiplying that by 1/r^2 gives d^2C/dr^2+ 2/r dC/dr so the equation is the same as D(d^2C/dr^2+ 2/r dC/dr)- kC= 0.

    Dividing the entire equation by D, then, gives eq. B.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Product Rule?
  1. Product rule (Replies: 2)

  2. Product rule (Replies: 19)

  3. Product rule (Replies: 3)

  4. The Product Rule (Replies: 2)

  5. Product rule (Replies: 3)

Loading...