The marginal cost (in dollars per square foot) of installing x square feet of kitchen countertop is given by C'(x)=x a) Find the cost of installing 50 ft of countertop. b) Find the cost of installing an extra 17 ft of countertop after 50 ft have already been installed. a) Set up the integral for the cost of installing 50 ft of countertop. C(50)= dx The cost of installing 50 ft of countertop is $ (Round to the nearest cent as needed.) b) Set up the integral for the cost of installing an extra 17 ft after 50 ft has already been installed. C(50+17)-C(50)= S dx 50 The cost of installing an extra 17 ft of countertop after 50 ft has already been installed is $ (Round to the nearest cent as needed.) 4