11. Let f(x,y)-x? + 2xy + y2 + 3x + Sy, Fin (2-3) and 2-3) 12. A farmer can produce f(x,y)=200/Gx2+y2 units of produce by utilizing xunits of labo and y units of capital. a. Calculate the marginal productivities of labor and capital when x b. 10 and y 5 Let h be a small number. Use the result of part (a) to determine the approximate effec production of changing labor from 10 to 10 + h units while keeping capital fixed at 5 u Use part (b) to estimate the change in production when labor decreases from 10 to 9, and capital stays fixed at 5 units c.