solve each formula for the specified variable 1/R=1/R1+1/R2+1/R3 for R help

Question

1/R=1/R1+1/R2+1/R3 for R help

Answer 1

1/R=1/R₁+1/R₂+1/R₃

LCM of R₁  , R₂, and  R₃ is R₁ R₂R₃

1/R=(R₂R₃+R₁R₃+R₁ R₂)/(R₁R₂R₃)

Apply Cross multiplication.

R₁R₂R₃= R (R₂R₃+R₁R₃+R₁ R₂)

R = (R₁R₂R₃)/(R₂R₃+R₁R₃+R₁ R₂)