Question 43240
Actually the best first step is to clear all fractions by multiplying by the lowest common denominator...here that is r*r1*r2...so we get
1/r = 1/r1 + 1/r2
r*r1*r2[1/r = 1/r1 + 1/r2]
r1*r2 = r*r2 + r*r1   then collect terms with r1 and solve
r1*r2 - r*r1 = r*r2
r1(r2 - r) = r*r2 and finally
r1 = r*r2 / (r2 - r)