Question: For c>0, the graphs of y=(c^2)(x^2) and y=c bound a plane region. Revolve this region about the horizontal line y= -(1/c) to form a solid. For what value of c is the volume of this solid a maximal or minimal (Use calculus 1 techniques). First, I found the volume of this solid using the washer's method and I got this answer: ∏ [(2c^2 +4)* square root of (1/c) - (2c^4/5)*(1/c)^(5/2) - (4c/3)* (1/c)^ (3/2)] I know that in order to find the maximum or minimum, I have to find the first derivative of the function and then use the sign chart, etc. But I am not sure whether I will have to use the volume I got above for the solid. Do I just differentiate only y=(c^2)(x^2) and find the critical values?