The solution to Exercise 29 is x = 10, y = 20, = 10. If 1

The solution to Exercise 29 is x = 10, y = 20, λ = 10. If 1 additional foot of fencing becomes available, compute the new optimal dimensions and the new area. Show that the increase in area (compared with the area in Exercise 29) is approximately equal to 10 (the value of λ).