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Please help me

  1. Sep 23, 2014 #1

    Can someone please explain me that what magic is done in second, third & fourth steps. I am totally lost.

    Thanks in advance.
  2. jcsd
  3. Sep 23, 2014 #2


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    Staff: Mentor

    That is not magic, just many simple re-arrangements of terms in the same step. Write them down, calculate the individual terms in the second line (including the prefactors like 1/30), find them in the first line and cross them out. Repeat for the other steps.
  4. Sep 23, 2014 #3


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    Might as well just multiply out the first line completely and see that all the terms cancel out. That would be a better proof than the obscure intermediate steps shown. Find the person who wrote those steps with no explanation. Then poke him in the eye. ;>) (Just kidding. That wink emotogram is not a wink -- someone poked me in the eye.)
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