Question 919418
if you have this:

 {{{1/R=1/R1+R2}}}.......... solve for {{{R}}}


{{{1/R=1/R1+(R1*R2)/R1}}}


{{{1/R=(1+R1*R2)/R1}}}..cross multiply


{{{1(R1)=R(1+R1R2)}}}


{{{R=R1/(1+R1R2)}}}


but, if you have this:


{{{1/R=1/(R1+R2)}}}


{{{1*(R1+R2)=1*R}}}


{{{R1+R2=R}}}