12. 13. 14. Calculate the partial derivatives 3;: and 3-5 using the chain rule for partial derivatives and the fact that f(:r:,y) = 3:2 + my, 3; = m) + 112, and y = 11.102. Let 2 = 3:2 + may 1:4 + y +39. Say :1: changes from 2 units to 1 units, and say y changes from 1 units to 3 units. Estimate the change in 2 by using a di'erential. Find the extrema of f(:z:, y) = 3:2 + my + 3,3. Classify these points as a maximum, minimum, or saddle