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Rewriting an expression what math operation did my teacher do?

  • #1
Femme_physics
Gold Member
2,547
1
Rewriting an expression....what math operation did my teacher do?

I'm trying to see how did my teacher rewrite this expression in the following manner:

[Broken]

What mathametical operation did he do? I really can't see it...
 
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Answers and Replies

  • #2
danago
Gold Member
1,122
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Have you definitely copied it correctly? If the S2 term in the denominator were S2/C then it would seem that he divided the numerator and denominator by RLC.
 
  • #3
MathematicalPhysicist
Gold Member
4,185
168
Simple algebraic manipulation, dividing the numerator by RCL and also the denominator.

He forgot 1/C in the denominator for S^2.
 
  • #4
HallsofIvy
Science Advisor
Homework Helper
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It looks straightforward to me. Initially, there is "SL" in the numerator while after the "operation" there is "S/RC". So the "S" is left alone and we have divided the numerator by 1/LRC. Dividing the denominator by that same 1/LRC gives (RLS^2+ LS+ R)/RLC= S^2/C+ S/RC+ 1/LC, almost what you have. Either your teacher accidently dropped the "C" dividing S^2 or there is some physical reason (you don't say, but I would guess this is an "LRC circuit equation) why that can be done although it does not look likely.
 
  • #5
Femme_physics
Gold Member
2,547
1
You guys are right, I miscopied! It's RLCS^2 and not RLC^2 at the denominator of the first expression..oops. Thank you, though, because saying what mathmatical operation he did cleared it out for me :-) I re-solved it and got the same answer he did!
 

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