SOLUTION: I cant get this for nothing 1/r = 1/R1 + 1/R2 :solve for R1 the R1 and R2 are subscripts

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Question 321568: I cant get this for nothing
1/r = 1/R1 + 1/R2 :solve for R1

the R1 and R2 are subscripts

Found 2 solutions by Fombitz, mananth:
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
1%2Fr+=+1%2FR1+%2B+1%2FR2
Multiply both sides by r%2AR1%2AR2
R1%2AR2=r%2AR2%2Br%2AR1
R1%2AR2-r%2AR1=r%2AR2
R1%2A%28R2-r%29=r%2AR2
R1=%28r%2AR2%29%2F%28R2-r%29

Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
1/r = 1/R1 + 1/R2 :
..
1/r-1/R2= 1/R1
..
R2-r/rR2 =1/R1
..
R1= rR2 /R2-r