contour plot for the function f (x, y). The values of the contours are labeled on the left side.a) At the point (2,1), is the partial derivative fx(2,1) positive or negative? Why?b) At the point (2,1), is the partial derivative fy(2,1) positive or negative? Why?c) At the point (1,2), what can you say about the partial derivatives fx and fy?d) Locate one point (x, y) where the partial derivative fx(x, y)=0. How do you know?e) Locate one point (x, y) where fx(x, y)<0. How do you know?