- #1

DespicableMe

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## Homework Statement

POwer P in watts, produced by an engine is P(R) = 130R / [(R+0.8)

^{2}] where R is resistance. What is the rate of change of power when R = 5?

## Homework Equations

## The Attempt at a Solution

I do not understand how the rate of change for this is

130/ ( (R+0.8)

^{2}) - 2(130R) / ((R+0.8)

^{3)}

I have tried plugging in R=5 into what I just typed above and I got the right answer. I just don't understand how they got to that equation.

One site wrote that the ROC of current with respect to resistance is 125/R

^{2}, for example, if current was 125/R

Can someone please clarify?