1/r = 1/r1 + 1/r2 if r=15 r1=23 then find r2

Step-by-step explanation:

1/R = 1/R1 + 1/R2

R = 15

R1 = 23

The best way to do this question is to convert the resistances to decimals.

1/R = 1/15 = 0.0666666

1/R1 = 1/23 = .04348

0.066666666 = 0.0438 + 1/R2          Subtract 0.0438 from both sides.

0.023188 = 1/R2                                  Take the reciprocal of both sides.

43.125 = R2

You can use fractions if you prefer. But it will a lot messier.

1/15 - 1/23 = 1/R2

23/345 - 15/345 = 1/R2

8/345 = 1/R2                      Take the reciprocal of both sides.

345/8 = R2

R2 = 43.125