Question 55717
Rr= 1
   ----
   1/R1+1/R2 Simplify the formula.
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Rr = 1/[1/R1 + 1/R2]
= 1/[R2+R1]/[R1*R2]
Invert and multiply to get:
Rr = {R1*R2]/[R1+R2]
Cheers,
Stan H.