SOLUTION: The reciprical of the combined resistance R of two resistances R1 and R2 connected in parallel is equal to the sum of the recipricals of the individual resistances. If the two resi

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Question 193073: The reciprical of the combined resistance R of two resistances R1 and R2 connected in parallel is equal to the sum of the recipricals of the individual resistances. If the two resistances are connected in series their combined resistance is the sum of their individual resistances. If two resistances connected in parallel have a combined resistance of 3.0 ohms and the same two resistances have a combined resistance of 16 ohms when connected in series, what are the resistances?
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
R1 + R2 = 16
R1*R2/(R1+R2) = 3 (A shortcut for the recip of the sum of the recips)
R1*R2/16 = 3
R1*R2 = 48
R1 = 48/R2
Sub for R1 into the 1st eqn
48/R2 + R2 = 16
48 + R2^2 = 16R2
R2^2 - 16R2 + 48 = 0
(R2 - 12)*(R2 - 4) = 0
R2 = 12 or 4
R1 = 4 or 12