Ex 83

The total resistance \(R\) produced by three conductors with resistances \(R_1, R_2, R_3\) connected in a parallel electrical circuit is given by the formula
\[\frac{1}{R} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3}\]

Find \(\partial R / \partial R_1\).