Solve the problem. 5) A rectangular playground is to be fenced off and divided in two by another fence parallel 5 ) to one side of the playground. 768 feet of fencing is used. Find the maximum area of the playground. 6) The daily profit in dollars of a specialty cake shop is described by the function 6) P(x) = -3x2 + 168x - 1920, where x is the number of cakes prepared in one day. The maximum profit for the company occurs at the vertex of the parabola. How many cakes should be prepared per day in order to maximize profit? Determine whether the function is a polynomial function. 7) f(x) = nx5+ 8x4+8 7) Find the degree of the polynomial function. 8) f (x) = 3x - x4 + 3 8) Find the x-intercepts of the polynomial function. State whether the graph crosses the x-axis, or touches the x-axis and turns around, at each intercept. 9 ) f ( x ) = -x2(x + 9)(x2 + 1) 9)