looks familiar ...
take the time derivative ...
get rid of the negative exponents and isolate ...
you have all the info for R1 and R2 ... calculate R from the original equation and determine dR/dt.
Ok two resistors R1 and R2 are connected parallel.
Total resistance is given by
R1 is 80 ohms & increases at 0.3 ohms per sec
R2 is 100 ohms & increases at 0.2 ohms per sec
so the question is now, "how fast is R changing at that time?"
not sure how to go about this question. any help much appreciated