1 4. (4 points) Find the points on the graph of the function y = :c3 + 69:2 11:1: 1 at which the tangent line is horizontal. If non exist, state the fact. m+1 5. (4 points) Find the equation of the tangent line to the graph of the function 11(3) = at 58 = 1. 6. (4 points) The revenue, in dollars, from the sale of m bottles of barbecue sauce is given by R(m) = 7 .5$0'7. Find the rate at which average revenue is changing when 81 bottles of barbecue sauce have been produced and sold. 7. (4 points) The cost, in dollars, of producing a: skateboards is given by C(53) = 900 + 18:307. The revenue, in dollars, of producing and selling a: skateboards is given by R(a:) = 75:303. Find the rate at which average prot is changing when 20 skateboards have been built and sold