Question

The total resistance R for three resistors R1, R2, R3 connected in parallel is determined by
1/R = 1/R1 + 1/R2 + 1/R3
i) Show that for i = 1,2,3, dR/dRi = (R/Ri)^2

Answer 1

You can use symmetry to apply it to all cases if you do just the \(i=1\) case.

Answer 2

symmetry??how to do that :(

Answer 3

Basically, let \(i=1\) and then differentiate, and then when you're done, put the \(i\) back in.