The energy required by a fish swimming at speed v to travel a distance L>0 in a current of speed u>0 is given by E(v) = aL((v^3)/(v-u)), v>u where a>0 is a proportionality constant. a) Find the speed of the fish which results in minimal energy expenditure. b) Give a qualitative sketch of the energy as a function of the speed of the fish. I know that I am supposed to isolate v from the equation by using another equation in order to differentiate it, but I don't know how to. As well as a is a constant, and all values are positive. Also when I am drawing the sketch will the value a still be included? How do I include this in a graph? How do I make an equation that involves both L and u in order to differentiate in terms of v?