Problem. 9 : Find the first partial derivatives of the function f(x, y) = 1x/1+y f1 = ? fy = Problem. 10 : Find the first partial derivatives of the function f(x, y, z) = yz' + xy' + xyz + xz fa = ? fy = ? f = = Problem. 11 : Evaluate the first partial derivatives of the function at the given point. f(x, y) = 4xBy-xy3; (3, 1 ) ? fx (3, 1 ) = ? fy (3, 1 ) = Problem. 12 : Find the second-order partial derivatives of the function. f(x, y) = x4+xy?+x+1 ? fry = fyr = fyy =Problem. 13 : Find the second-order partial = derivatives of the function. f{x,y}=1+10y I\" = f,\" = I f\" = is, = I Problem. 14 : The productivity ofa country in South America is given by the function x, 3;) = 40r'i5v1", when m units of labor and 3,- units of capital are used. {a} What are the marginal productivity of labor and the marginal productivity of capital when the amounts expended on labor and capital are 243 units and 3125 units, respectively. (Round your answers to two decimal placa.) labor I units capital units {l1} Should the government encourage capital inventrnent rather than increased expenditure on labor in order to increase the country's productivity? Enter 1 for \"yes\" or I) for \"no.\