Question 1147924
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<pre>

Given


    {{{1/R}}} = {{{1/r[1]}}} + {{{1/r[2]}}}.


Then


    {{{1/R}}} = {{{r[2]/(r[1]*r[2])}}} + {{{r[1]/(r[1]*r[2])}}} = {{{(r[1]+r[2])/(r[1]*r[2])}}}.


Hence,


    R = {{{(r[1]*r[2])/(r[1]+r[2])}}}.    <U>ANSWER</U>
</pre>

Solved.