3. [5 points] Given that f is a differentiable function with f(2,5) = 10, fa,(2, 5) = 1, and fy(2,5) = 1, use a total differential to estimate f(2.1,4.8) 4. [5 points] A company nds that it takes 3; units of labour and y units of capital to produce fwd!) = 100m3/4y1/4 engines. A unit of labour costs $100 and a unit of capital costs $200. The company has decided to manufacture 2,000 engines. Find the amount of money they should spend on labout and capital to minimize their production cost