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# Help with manipulating an equation Watch

1. Maybe its revision taking its toll or what, i dont know, but i cant seem to work out how the lecturer manipulated the first equation to change it to the second.

http://i52.tinypic.com/1zacjn.jpg
2. He has done more than rearrange it, otherwise 1 / bracket in the first equation = the bracket in the second equation and that isn't true.

Perhaps post in engineering or physics?
3. (Original post by Ewan)
He has done more than rearrange it, otherwise the bracket in the first equation = the bracket in the second equation and that isn't true.

Perhaps post in engineering or physics?
he must have, but unfortunately he just jumps from one eqn to the other.

The thing is, the algebra leading up to those equations is very simple, but the bit in the image just threw me off completely
4. Well I don't even understand most of the words on the paper so can't help sorry
5. this is just rearraging, just make sure you write out all the steps, otherwise it's hard to visualise.

first of all, times by 4, then divde by V, then divide by the big bracket, ( or flip it and times it) now you have dR/R = (4Vo/V)(1+(dR/2R))

now times the bracket, giving (4Vo/V) + (2VodR/Rv)

then move the second term to the left:

(dR/R)-(2VodR/Rv) = (4Vo/V)

factorise:

(dR/R)(1-2Vo/V) = (4Vo/V)

then divide, to giving the answer shown on the screen

(dR/R) = (4Vo/V)/(1-2Vo/V)
6. thanks mate thats sorted it
7. no problem

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