Question

how do you find the derivative of the function (1/R) = (1/r_1) +(1/r_2) ?

Answer 1

I had R^-1 = r_1^-1 +r_2^-1...and then I got lost.

Answer 2

I've also cross multiplied so that \[1/R = (r_2 + r_1)/(r_1r_2)\]

Answer 3

But I don't know how to get the derivative of that either.

Answer 4

What are you trying to take the derivative with respect to?

Answer 5

t, x,y,z...?

Answer 6

with respect to R

Answer 7

I need to show that R is a increasing function of r_1

Answer 8

r_2 is a constant

Answer 9

gotcha