(7) Find the lengths of the sides of a rectangle with perimeter 20 with maximum possible area. (8) Determine where the function y = f(x) = x - 12x is increasing or decreasing. Identify all of the relative maxima and minima. (9) Determine where the function y = f(x) = x - 12x is concave up or concave down. Identify all of the inflection points. (10) Find the relative maxima and minima of f(x) = x3 - 6x2 + 9. Verify your conclusions using the second derivative test