Question 68815
simplify this formula? 
RT =1/(1/R1 + 1/R2)----


Simplify the denominator:
1/R1 + 1/R2 = (R1+R2)/R1R2
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Now take the inverse of the denominator to get:

RT= (R1R2)/(R1 + R2)
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Cheers,
stan H.